ADDITIONAL REFERENCES
INTRODUCTION
You will be privileged to perform these experiments and will find you may
even survive this course if you follow the instructions given, paying
particular attention to the warnings, cautions and notes in the instructions.
With the exceptions noted in the instructions, it is your responsibility to
read, and know how to perform, the experiments the day before your group is to
do the experiments.
The experiments are to be written up as follows: One member of each group
will turn in a complete write up on each experiment with all other members
turning in those parts which are marked (*). A carbon copy of these parts from
the original write up is acceptable. (All examples are for some form of
experiment 1.)
1. Introduction - A brief statement of what is to be found and how.
Example: In this experiment the acceleration of gravity is to
be determined using a free fall type apparatus with a spark
timer.
2. Theory - If you are asked to, or want to, derive an equation or
equations, you will use this section for that purpose. If no
derivations are to be done, list the sources (book and page
number) of the equations that you used.
3. Procedure - A brief statement of any deviations from the normal
procedure given in the instructions is all that is necessary.
If you followed the instructions reasonably closely, just state
that.
4. Data - Neat tables listing the data obtained. A carbon copy of
the original data sheet must be turned in after performing each
experiment but before leaving and be with each member's report.
It may be rewritten if the original is not as neat or clear as
possible, but the original must also be turned in. (*)
5. Sample calculations - One or two clearly written out examples of
how your results were calculated.
6. Results - A table giving the results you obtained and a sentence
or two or table giving the averages from the many similar trials
made. (*)
7. Error analysis - A brief table listing the error expected in
each type of measurement, the total expected error and the
actual error obtained as a percent of the theoretically expected
result. If your actual error percent falls below the expected,
you only need to say the error is less than expected, but if
your percent is greater than expected, you must explain why, to
the best of your knowledge, the expected error was exceeded.
Where you are trying to compare values obtained from two
equations or are trying to compare the two sides of one
equation, the theoretical value will be that obtained from the
equation using distance, mass or angles of the parts of the
system, while the actual values will be those obtained using
time related values of the system as a whole. In some cases, no
theoretical value can be obtained so all that you need to do is
to calculate the expected error on your results. (*)
8. Conclusions - Write a sentence or two on what can be concluded
from your results.
9. Answers and comments - Answer any questions asked in the
instructions and comment briefly on possible improvements to the
experiment. If the instructions ask you to explain something or
ask why something is as it is, use this section.
In several experiments you will be required to obtain the rate of change
of some quantity from a series of data points, either recorded on spark timer
paper or obtained from a progressive series of additions to previous data
readings. There are many ways of evaluating this type of data, but most methods
result in the net effect of only using the end points of your data. The method
which you will use is the only one which allows all of the data points to be
used. I call this method the method of differences and it works as follows:
Number your data points and divide them into two approximately equal
groups (example - for 12 points, the first six would be in the first group
and points 7 through 12 in the second). So far so good. Now, subtract
successive elements in the first group from those in the second (7-1, 8-2,
9-3, etc.). Confused yet? If not, read on. Since this method will only be
used to determine the rate of change of some quantity, (Ds/Dt, Dv/Dt,
DF/Ds,etc.) you will need to know the other variable. When calculating any
rate of change, both quantities must be over the same interval, therefore you
simply (?) determine the interval for the first quantity and use the
corresponding interval for your other variable (example: if you are timing
and have a half second between points, the time interval between the first
and seventh points is 3 seconds).
In order to ease your misery, computer programs are available to do most
of your calculations. Programs for experiments 1, 7, 25, 38 and 46 will be
available. It will be your responsibility to run these programs.
The experiments will be graded on an eleven point scale if they are
completed and turned in within one week of the day you are assigned to do the
experiment. They will be graded on a ten point scale if turned in later than
one week after the assigned day, but before the final due date. If turned in
on the due date, they will be graded on a nine point scale. Experiments turned
in after the final due date will be graded on a ten point scale, but will be
penalized two points per day (including weekends) late, up to a maximum of
minus twenty.
You may replace one experiment per marking period with an original one of
your own choosing. The due dates and grading are the same as for all other
experiments and the same general rules apply as those listed in experiment 41.
During the fourth marking period, an original, ongoing experiment, started
before mid-year may be used to replace experiment 41 and one or more others,
depending on the complexity and originality of your experiment (a science fair
project would be a good example).
The following abbreviations will be used in describing the references:
IIT lm - Illinois Institute of Technology General Physics Lab. Manual l956
H&R - Halliday and Resnick 1966 (dark blue)
S&Z - Richards, Sears et. al. 1962 (grey)
M - Miller 1967 (green)
S - Schaumns Outline 6th ed.
QC - Quick Calculus 1965
THINK - DO YOU REALLY WANT TO GO ON?
EXPERIMENT 1 - THE ACCELERATION OF GRAVITY
This experiment uses the free fall apparatus set up in the back room (the
tall pipe with the heavy tripod base and spark timer). Run the wax coated
paper up from the bottom and through the top of the apparatus with the wax
coated side out (it should be on the front of the support pipe, just in front
of the wire next to the pipe), use the chained on clip to hold it taut and
position the paper slightly off center so you can make more than one run on
each piece of paper. Turn on the electricity (both the large panel and the
spark timer) and hang the plum-bob (the string with the bolt on one end), with
the pointed end up, on the bottom of the blue magnet, point to point. Using
the leveling screws at the base, center the bolt exactly between the wires.
Replace the plum-bob with the falling body (pointed end up). Make sure that
the timer is turned on for at least a minute and leave the master switch on
until you are done with all of your trials. Slightly before one of your group
members turns off a circuit breaker on the electrical panel, another member
should press AND HOLD the spark switch on the spark timer. The same person
should not do both as this could lead to a very shocking experience! This
should produce a series of spark dots on the waxed paper and if the spark
switch is held down too long, it will also produce flames which will quickly
consume your data. Using the method of differences, determine the
acceleration of gravity. NOTE: You will need to use this method twice, the
first time to get velocity and the second to get the acceleration. Average
this second set to get the acceleration of gravity. The spark timer produces
60 (0.1) sparks per second. You should make at least three trials and at
least one must be worked out by hand. The other trials may be calculated using
LONGESTM.
References: IIT lm 22, H&R 48, S&Z 62, M 35, S 27, QC 138
EXPERIMENT 2 - THE ACCELERATION OF GRAVITY
Use the long bar with the crossarm on one end. Support this such that it
swings freely between two lab tables (you will need two support rods and one
crossbar). Start the bar swinging with some initial angle (the exact angle
need not be known as long as all trials use about the same angle) and, using a
stopwatch, determine its period, averaging several trials and allowing the bar
to make several swings each trial. Tape a strip of carbon paper and white
paper to one edge of the bar. Should this affect the period? Attach a metal
ball to one end of a piece of string and run the string over the top of the
bar, attaching the other end through the hole at the bottom of the bar such
that the ball just barely touches the floor. Pull the string, using only two
fingers of one hand, so that the ball comes to the top front corner of the bar
and, at the same time, the bar is pulled to approximately the same angle used
previously. When you release the string, the bar should swing down and hit
the falling ball, leaving a carbon spot on the paper. Since you know the time
for the bar to swing to the vertical is 1/4 of the time to make one complete
swing, and also the distance that the ball fell, you can easily calculate the
acceleration of gravity using S = 1/2gDt2. Make several trials and use several
different balls. Should the type of ball make any difference? Average your
results and explain any major differences.
References: IIT lm 47, H&R 48&140, S&Z 62&229, M 35&195, S 27&84
EXPERIMENT 3 - THE BALLISTIC PENDULUM
A gun and catcher arrangement will be used for this experiment. Set up
the apparatus on a level surface, remove the pendulum, determine its mass and
that of the ball, determine the center of the mass of the pendulum with the
ball inside, then replace the pendulum in its holder. Place the ball on the
end of the gun's rod and carefully cock the gun by pushing on the ball. Use
care so as not to bend the rod. Fire the ball into its catcher. The ball
should stay in the catcher, with both swinging up and catching on the ratchet.
If this doesn't happen, check to see if everything is carefully aligned.
Measure the height increase of the CENTER OF MASS of the pendulum and ball at
least five times. By knowing the mass of the ball, the mass of the pendulum,
its increase in potential energy (where did this extra energy come from?) and
that you had an inelastic collision, determine the average velocity of the
ball as it entered the pendulum. This is your theoretical value. Next,
determine the velocity of the ball from its range. Using an open area, fire
the gun horizontally off of one of the tables and note where the ball lands.
Tape a piece of paper at this spot, place carbon paper on top of this so that
when you fire the ball for five trials, five carbon spots will be left on the
paper (NOT the floor). By knowing the height of the gun and the distance from
the spots to a point directly below the end of the rod, you can also determine
the average velocity of the ball. For a second check, tilt the gun upward.
Shooting from the back of the table so the gun rod doesn't hook, find the range
(from the end of the rod), height from the floor to the end of the rod and
angle of the gun (if you're careful, a 30o angle is useful) determine the
average velocity using five trials. Explain any major differences.
References: IIT lm 41, H&R 219, S&Z 167, S 63
EXPERIMENT 4 - PROJECTILE MOTION
A steel ball is allowed to roll down an inclined tube with an inclined
lower end. The object of this experiment is to use your vast knowledge of
physics to show that you can calculate where, within experimental limits
(which are what?), the ball will land. Use a level to determine the angle of
the lower part of the tube. Measure the height of the top of the tube above
the bottom of the tube and the height of the lower end above the floor in
centimeters, including any estimated uncertainties. Calculate Vo (the
velocity as the ball leaves the tube) using the law of conservation of energy.
Calculate how far horizontally from the lower end of the tube the ball should
land. Tape a piece of paper on the floor above the landing site and put a
piece of carbon paper over the spot and roll the ball down the tube. If the
ball landed more than a few centimeters away from the calculated spot, find
other factors not previously considered and repeat the calculations. Your
experiment is complete when your calculated spot agrees with what you obtained
experimentally.
References: H&R 59&272&281, S&Z 104, M 44, S 31, IIT lm 45
EXPERIMENT 5 - ATWOOD'S MACHINE
Atwood's machine is just a horrifying name for a set of freely moving
masses attached by a string over a pulley. The equation which you are to
derive is a = ((m1-m2)g/(m1+m2))+af where a is the acceleration of the system,
m1 and m2 are the masses and af is a fictitious acceleration due to friction.
Hang several masses (m1) on a string passing over the pulleys in the front of
the room and balance these with a like amount of mass (m2) on the other end.
The total mass (m1+m2) should be 600g - 1100 g. Throughout the entire
experiment, m1+m2 MUST remain constant. The string should be somewhat longer
than the distance from the floor to the pulleys. Remove some mass from one
side and add it to the other. Release the system and time its fall. Using
S = 1/2aDt2, a may be found. Do this several times, averaging your
results. Now, take more mass off of the light side and add it to the heavy
side and repeat the process. Make several different trials with different
mass distributions. You will note that when m1-m2 becomes large, the smaller
weight may fly off when it reaches the top, therefore you should either be
clear of other groups and especially observant so you don't get hit, or
supply everybody with hard hats. To find af, make a graph of a vs. m1-m2,
the point where this straight line (if it isn't straight, explain why)
crosses the a axis is af. Using this value, check each previous set of data
for accuracy. a is your actual value since it was found by measurements on
the complete system, while the right side of the equation is the theoretical
value since it involves the measurement of parts of the system.
References: IIT lm 22, H&R 101, M 66, S 41
EXPERIMENT 6 - BOUNCY-BOUNCY
The period of oscillation of an object bouncing on a spring will be
obtained physically and theoretically in this experiment. The experiment will
use a spring, a number of 50 and 100 g masses, a meterstick and a timer.
Suspend the spring and attach enough weights to separate the coils slightly.
Use this position as your starting position. Take ten readings, increasing
the mass on the spring by the same amount each trial and record the mass,
weight and position relative to the starting point. Use the method of
differences to determine the force constant of the spring, DF/Ds=k and
average these. Attach 300g - 700g to the end of the spring and start it
oscillating up and down. Accurately determine the period, possibly averaging
several trials of 20-30 cycles each. Do this for at least three different
masses. Determine the mass m' of the spring. Calculate the theoretical
period of the spring using the equation (which you will derive)
T = 2pi*sqrt(((m'/3)+m)/k). Compare these values with those obtained with a timer.
References: IIT lm 32, H&R 345, S&Z 217-218, M 187, S 83, QC 122&272
EXPERIMENT 7 - NEWTON'S SECOND LAW
Here it is folks, your chance to prove (or disprove as the case may be)
that infamous equation F=ma. Your apparatus consists of a heavy cart, its
track, several masses and the same spark timer used in experiment 1. Support
the track high enough off of the floor so that the small wire used to pull the
cart will just reach the floor as the cart reaches the end of the track. Then
level the track. Fasten the waxed tape across the top somewhat off center (so
one tape can be used for several runs) between the points on the cart. Hook
the spark timer to the track and the terminal on the pulley support. The
ground wire should go to the track. Place 200g on the cart and 100g on the
wire. Release the cart and start the timer. Unless you would like a large
charge from this experiment, different members of the lab group should release
the cart and start the timer. Repeat this with 150 on the wire and 150 in the
cart. Try a third run with 200 on the wire and 100 in the cart and finally,
use all 300g on the wire. You must determine the acceleration for each of
these trials in a manner similar to experiment 1. One trial must be done by
hand while the rest may be run through the computer using LONGESTM. Note: you
don't need to use every point, every 6th, 10th, or 30th is OK as long as you
use the corresponding time interval and have at least 16 data points left.
Plot a vs. F on a graph, the point where this line crosses the F axis is the
frictional force. Since a = F/m, the slope of this graph should be 1/m, where
m is the total mass being accelerated. This slope gives you a theoretical value
for m. Subtracting the frictional force from the force on the end of the wire,
calculate the acceleration in each trial and compare this value to the actual
acceleration of the cart.
References: IIT lm 25, H&R 85, S&Z 83, M 58, S 35, QC 138
EXPERIMENT 8 - THE NON-VERTICAL PENDULUM
This is a swinging experiment. Use a table in the front of the room
with a frictionless puck attached to the edge by a string 1 meter long. In
order to eliminate interference, run the air hose through a clamp mounted
about a half meter above the edge of the table. Tilt the table 4o-6o,
turn on the air and determine the period of oscillation. Tilt the table
more by putting books under the legs. As the slant becomes greater,
support the table from the other side. Plot a graph of period vs. angle,
using at least 25 points. Knowing that the period should be
T=(f(theta))*(2pi sqrt(L/g)), guestimate what f(theta) should be, then go back
and plot this theoretical graph on the same paper as the experimental graph,
explaining any differences.
References: QC 9&38
EXPERIMENT 9 - SPHERICAL SURFACE PENDULA
Part 1: Using balls of various radii (at least three different), allow
them to roll back and forth in two bowls of different radii, keeping the
amplitude small so that no sliding takes place. What would happen to your
results if they did slide? Record the radius of the ball r, the radius of the
surface R and the period. Calculate the period using T = 2pi sqrt[(7(R-r))/5g]
(which you will derive) and compare this theoretical value with your
experimental value. You will need to use a spherometer to determine the radii
of the bowls, so a bit of research before coming to class would be helpful.
Part 2: Using the short air track and small carts, clamp the center down
and allow the cart to oscillate back and forth, timing the motion. Prove
experimentally and theoretically that this period is equal to the period of a
pendulum whose length is that of the radius of curvature of the track.
References: IIT lm 109, H&R 118, S&Z 117
EXPERIMENT 10 - FRICTIONLESS ACCELERATION
With the air track apparatus, (air track, vacuum and variac, keeping the
pressure just high enough to allow the cart to float freely) determine the
acceleration of the cart for various angles of elevation of the track using
S = 1/2at2. Derive an equation for the acceleration in terms of the angle
(or some function of the angle) of elevation. Note: A protractor or angle
finder is not accurate enough and you should consider how to find the sine
of the angle using only a meterstick. Does the mass of the cart make any
difference? Using the cart with the water container on it, check the
direction of 'down' in this accelerated reference frame and attempt to
justify your findings. DO NOT let the water cart hit the end of the track.
Your angles should generally be less than 2o-4o.
References: S 43
EXPERIMENT 11 - ROTATING MASSES
Obtain a turntable, the T holder and a small mass. Attach the mass to
the T holder using some suitable length of string (L) and allow it to rotate.
Using your vast (?) knowledge, determine experimentally the angle (theta) that the
cord makes (describe your procedure). Derive an equation giving the angular
velocity of the turntable in terms of L, and r (the distance from the center
or the holder to the hook). Note: You will probably get an equation giving
the angular velocity in radians per second. In order to convert to
revolutions per minute, multiply by 30/p. Average your values for the same
turntable speeds but different arm lengths and compare these with the actual
turntable speeds. (You should have 4 trials for each of 4 speeds.)
References: H&R 66, S&Z 112, M 155, S 71
EXPERIMENT 12 - STREAM VELOCITY
This experiment is all wet. Use the plastic container with three holes
in the side, the top with the tube and the tank to catch the water. Plug the
two top holes and place the stopper with the eyedropper in the bottom hole.
Fill it almost full with water and place the top on it with the tube 4-7 cm.
below the surface of the water. Use a sealer to seal the top. When water is
allowed to flow out of the eyedropper, its velocity should be constant (prove
it). By using the equations given in the reference, you will be able to
determine the velocity of the stream as it leaves the dropper. Note: the
surface of the water is considered to be where the air is entering. You
should also find the velocity by using the height and range as you did in
previous experiments. Explain any differences.
References: H&R 458 (prob. 9), S&Z 207, M 260, S 94
EXPERIMENT 13 - TWO DIMENSIONAL EQUILIBRIUM
Using the force table supplied, balance three UNEQUAL forces such that
their point of application is directly over the center pin. Prove graphically
and algebraically that the resultant of these forces is equal to zero. For a
second trial, use four UNEQUAL forces, proving algebraically and graphically
that the resultant of three of these is the equilibriant of the fourth. No
error analysis is necessary but if the sum is not zero, explain. In general,
what can be said about any one force acting on a point in equilibrium if there
are n-l other forces also acting on this point?
References: IIT lm 36, H&R 320, S&Z 20, M 86, S 1, QC 25
EXPERIMENT 14 - THREE DIMENSIONAL EQUILIBRIUM
Arrange at least three spring balances on two or more different supports
such that you have lines running from the balances to some common point
between them and hang at least 10 nts. from this point. The balances can be
tied to any point as long as the lines do not fall in the same plane. Use
your imagination to construct a system. Prove either algebraically or
graphically that any one of the forces is equal to the vector sum of all of
the others. If you solve your system algebraically, comment on the geometric
solution and, likewise, if you solve your system graphically, comment on how
you could also solve it algebraically. Comment on the problems encountered
when measuring angles in three dimensions. Sketch your arrangement.
References: IIT lm 36, H&R 320, S&Z 20, M 86, S 1, QC 25
EXPERIMENT 15 - THE YO
Your apparatus for this experiment is two large pieces of masonite, one
round, the other square, a meterstick, caliper and timer. Hang the disk such
that it will roll down and back up without touching the string. Knowing the
time it takes to go down and back up, (the average of several trials) using one
half of the total time to compensate for the frictional forces and also, by
counting the number of turns it makes going down and back up, again using one
half of this number, you can calculate the angular acceleration of the disk on
its way down. You should justify the use of a half of the time and turns in
your error analysis. The torque can also be calculated by taking the weight of
the disk times the moment arm (the radius of the axle plus the radius of the
string). Why is the radius of the string used? Using the rotational equivalent
of Newton's Second Law, the radius of gyration of the disk may be found (you
only need to find the radius of gyration). Note: If you solve your equations
symbolically first, you should find that you don't need the mass of the object.
The radius of gyration may also be calculated using the physical properties of
the disk. Repeat the above using the square.
References: IIT lm 27&45, H&R 286, S&Z 179&183-186, M 156&165, S 67&75
EXPERIMENT 16 - THE MOMENT OF INERTIA OF A LONG ROD
With the rod and axle, metal rails with supports and several weights, you
will determine the moment of inertia for a long thin rod. Set the rod so that
it rolls on its axle along two rails. Hang a weight on the end of the string,
allowing the rod to rotate freely from rest and time one revolution. Calculate
the average angular velocity of the rod during this one revolution. Do this for
2, 3, 4, etc. revolutions, measuring the time for each respective number of
revolutions and calculating the average angular velocity during this interval.
(Where, during the time interval for each trial, does the average occur?) Plot
v vs. t, noting that the line is not straight, but curves as the number of turns
increases (why?). By taking the slope of this line at its straightest interval,
the angular acceleration can be obtained. Do this for several different weights
and plot on another graph, weight vs. acceleration. The point where this graph
crosses the weight axis is the frictional force. As in experiment 15, the
moment of inertia may be found since you know the angular acceleration and
torque. Calculate the moment of inertia for each weight used and average your
results. From this average, determine the radius of gyration of the rod. Obtain
a theoretical value from the physical properties of the rod for the radius of
gyration and moment of inertia.
References: IIT lm 27&45, H&R 286, S&Z 179&183, M 156&165, S 67&75
EXPERIMENT 17 - THE MOMENT OF INERTIA OF A CYLINDRICAL DISK
Happiness is finding an easy experiment. Better luck next time. The
apparatus for this experiment is set up in the project room. You should
notice that there is a heavy steel disk with a string attached to its axle
and passed through a pulley for this experiment. Place a weight (W) on the
end of the string large enough to accelerate the disk (about 5-10 Nts.) and
allow the weigh to fall, timing the fall. Do this at least three times for
the same weight and distance (h) of fall. Average these three trials (the
times of fall and return height). Repeat the above procedure with three
different weights. Average these trials, their times and distances of
fall. Using S = 1/2at2, find the linear acceleration of the descending
weight. This is also the tangential acceleration of any point on the axle.
Find the frictional forces acting on the disk by allowing the weight to
rise again during each trial. Measure the return height (h'). The
frictional force is then given by f=W(h-h')/(h+h') which you should derive
by knowing that the loss in potential energy equals the work done by
friction. Note: all distances are measured from the lowest point in the
travel of the weight. The acceleration force (F) is just the weight minus
the frictional force. Therefore the accelerating torque is Fr where r is
the radius of the axle plus the radius of the string. Since the radius r
and the tangential acceleration are known, the angular acceleration may be
calculated using alpha = a/r. Therefore, the moment of inertia (I) may be
found from I=Fr/alpha. As a check, and to obtain a theoretical value, the
moment of inertia should be calculated using I = 1/2MR2. Here, R is the
radius of the disk and M is the mass of the disk. The mass must be
calculated by multiplying the disk's volume by its density (7.83g/cm) since
you may NOT remove the disk for direct measurement of its mass. The disk's
radius is 4 inches. The most common error in this experiment is having
inconsistent units.
References: IIT lm 27&45, H&R 286, S&Z 179&183, M 156&165, S 67&75
EXPERIMENT 18 - THE GYROSCOPE
The purpose of this experiment is to study the motion of a gyroscope.
The apparatus consists of a bowling ball rotating in a socket and two timers.
Friction is reduced by supporting the ball on a thin film of air. On the ball
is mounted a removable steel shaft. The system is set into rotation by
spinning it with your hand and the average number of revolutions per minute is
obtained with the help of a timer. The period of precession is simultaneously
checked with another timer. The equation you will attempt to verify is:
tau (Torque) = w (angular velocity of precession) X L (angular momentum of
the system). Since the angular momentum of the ball is much greater, we
can neglect the rod and express this equation as (f/T)=(3.799)(m1r1)g/(MR2).
You should derive this in your report. Here f is the average rpm for each
trial, T is the period of precession, m1 the mass of the shaft, r1 the
distance from the center of the ball to the center of the shaft. M is the
mass of the ball and R the radius of the ball. Use the right side of the
equation as the theoretical and the left side as the experimental values.
The average rpm should be the number of revolutions divided by the time (in
minutes) of precession. CAUTION!!!!! Should the air be suddenly cut off
or the ball not started correctly, it is possible for the ball to gyrate
erradically, geometrically building up until either the ball pops out of
the socket or the rod flies out. Therefore, should the ball start to
wobble, reach in and gently steady it or duck!!
References: IIT lm 27&45, H&R 286, S&Z 179&183&195, M 156&165&179, S 67&75
EXPERIMENT 19 - BOYLE'S LAW
You are to, with the aid of a graph, show that Boyle's Law checks within
the limits of experimental error.
References: H&R 433&572, S&Z 350, M 305, S 114
EXPERIMENT 20 - CHARLES' LAW
Obtain a boiler stand, burner, thermometer, glass tube with mercury bead,
ice (or snow) and salt. Mix the ice (or snow) and salt in the boiler to obtain
a mixture 5-10oC below zero. If you are using snow, alternate layers of
packed snow and salt and add about 250ml of cold water when you have the
boiler full. Insert the glass tube and thermometer through the two hole
stopper, keeping the thermometer bulb even with the midpoint of the lower
portion of the glass tube. Why? Plot a graph of height of bead vs. temp. as
the mixture is heated. What difficulties were encountered in measuring the
height of the bead? Extrapolate your graph down to zero height. What
temperature does this represent? Why do the top and/or bottom points not fall
along the general line of the other points? Note: Thoroughly rinse off all of
your equipment after the experiment as the hot salt water causes very rapid
rusting.
References: M 317, S 114
EXPERIMENT 21 - THE HEAT OF FUSION OF WATER
You are to, with the aid of a perfectly insulating calorimeter (styrofoam
cooler), determine the heat of fusion of water. You should have about 1000g
of water and must use ice, snow won't work. (why?)
References: IIT lm 88, S&Z 310, M 292, S 124
EXPERIMENT 22 - THE HEAT OF VAPORIZATION OF ALCOHOL
Here is an experiment to get you steamed up. Determine the heat of
vaporization of alcohol. CAUTION ---- Alcohol is highly combustible.
Insert a thermometer in the boiler and heat with a low flame until the
temperature reaches the boiling point (how can you tell?). While you are
heating the alcohol, the outlet tube should be immersed in some extra water
and the tube should be watched so it doesn't kink and allow the internal
pressure to build up as these vapors are explosive. (BOOOMMMMMM!!!!) While
it is boiling, insert the outlet tube into the calorimeter water, keeping it
away from the styrofoam.
References: IIT lm 86, H&R 563, S&Z 310, M 292, S 124
EXPERIMENT 23 - CALIBRATING A THERMOPILE
Using the thermopile supplied, attach the chart recorder to its terminals
and use a ring stand to support the pile with the junctions facing down. One
set of junctions should be thermally insulated to maintain a uniform reference
temperature. The other junctions will be used as the measuring junctions.
The recorder should be set on standby except during actual runs, the speed
should be about 1 cm./min. and the sensitivity set using the match flame on
one junction to give slightly less than full scale deflection. Using an ice
salt mixture and a process similar to experiment 20, record the temperature on
the chart every 5o-10o. Repeat the above process 2-3 times, gently bending
and insulating a different number of measuring junctions each time. Finally,
determine the temperature of a match flame by insulating all but one of the
junctions, heating this one and extrapolating the results of your previous
graphs.
References: S&Z 285, M 460
EXPERIMENT 24 - THE MECHANICAL EQUIVALENT OF HEAT
It is most convenient if you perform this experiment in the dark room.
Use the heating coil supplied, insert two thermometers in the stoppers and
connect the sink drain, one of the other tubes goes on the water faucet and
the third one goes to the heating coil. A short hose with clamp then goes
from the other end of the heating coil to the sink. In order to avoid the
fountain effect requiring a large amount of cleaning up, turn the water on
slowly, allowing water to flow out through the overflow and coil. The
overflow will probably gurgle. The flow of water through the coil should be
adjusted by moving the coil's outlet tube or readjusting the clamp. The flow
will probably be very small but some flow must be present at all times. Using
the D.C. power supply, the electrical terminals are hooked up as follows: one
end of the coil directly to one of the terminals, the other end to the
ammeter, then from the other end of the ammeter to the other D.C. terminal.
Use the 10 amp scale. The voltmeter should be connected directly across the
coil using the 5 volt scale. In order to avoid damage to the equipment and
the wrath of the instructor, the proper polarity on the meters must be used
and the hookup should be checked before the electricity is turned on. If more
than one ammeter is supplied, hook them up in series and average their
readings. Obtain a reading of somewhat over 6 amps and adjust the water flow
to obtain a temperature difference of 3-10Co across the coil. Note: There
must always be some water flowing from both the overflow and the coil drain.
Make several trials at different currents and water flow rates. The
mechanical equivalent of heat can be determined by measuring the quantity of
water heated in a given time, the heat output and the work input. Do not
leave the current on any longer than necessary since the power supply gets
quite hot.
References: IIT lm 82, H&R 554, S&Z 306, M 288, S 130
EXPERIMENT 25 - THE CONSTANT VOLUME GAS THERMOMETER
Using the idea that the pressure of a gas is directly proportional to
the kelvin temperature of the gas provided the volume is constant (an idea
you will derive), plot and explain the shape of a cooling curve of a beaker
of hot water exposed to room temperature vs. time. To obtain the curve,
boil water with the closed flask in it and, with the water still boiling,
hook the tube from the flask to one side of the manometer, then shut off
the heat. You should use the atmospheric pressure as your standard and the
boiling point of water at that pressure (in degrees Kelvin) and keep the
volume of the confined gas constant by raising or lowering the open arm of
the manometer to keep the closed atmospheric pressure reading should be
taken at specific, uniform time intervals, possibly every minute or two.
It is possible to obtain a computer printout for the results. Explain the
graph and your results.
References: H&R 529, M 282
EXPERIMENT 26 ELECTRIC FIELD NEAR SEVERAL CHARGE DISTRIBUTIONS
Using the two boards supplied with this experiment, you are to
experimentally determine equipotential surfaces and, from these, draw the
electric field lines. For this experiment, use the board with only two bolts
and the board with only one bolt and a COMPLETE border. The black paper on
these boards is a conducting paper which is expensive and can be damaged if
handled roughly. Connect the center bolt of the single bolt board to the +
(red) terminal on the small green power supply and the border to the - (black)
terminal. Plug in and turn on the VTVM (set to the 15 volt DC scale) and then
connect the black (gnd) lead to the black wire attached to the border. Then,
using the other VTVM lead as a probe, find enough points at some single
potential to enable you to get a good idea of what this 'surface' is shaped
like. Repeat this for at least three other potentials. It might be easier if
you just transfer the coordinates onto graph paper directly from the board,
using different colors to represent the different potentials. When you have
done this for the board with a single bolt and complete border, then do the
same thing for the board with the two bolts, only connect the + lead to one
bolt and the -to the other. From these equipotentials, construct the field
lines and indicate whether they look like what you expected (or what the book
predicted). Note: you will be sharing the power supply with the group
performing experiment 27, so set it up someplace convenient to both groups.
References: H&R 670, S&Z 387, M 364, S 136
EXPERIMENT 27 ELECTRIC FIELD NEAR SEVERAL CHARGE DISTRIBUTIONS
Following the same general procedure as that of experiment 26, plot the
equipotentials and field lines of the following charge distributions:
1) Use the board with four bolts and connect three of the
bolts to the + on the power supply and the remaining one
to the -.
2) For this trial, use the board with one bolt and a border
on ONLY ONE side, connecting the + from the power supply
to this bolt and the - to border.
In both experiment 26 and 27, how do your plots compare with the theoretically
predicted plots? If there are any major differences, explain them.
References: H&R 670, S&Z 387, M 364, S 136
EXPERIMENT 28 - THE CHARGE ON THE ELECTRON
With the help of several pieces of equipment, the charge on the electron
may be found. You will need the D.C. power supply, a graduated cylinder,
clamp, tongs, timer, ammeter, platinum electrodes, sulfuric acid and
container. WARNING!!! ---- The acid is very corrosive, if any acid enters
the electrodes, gets on skin or clothing, promptly wash it in cold water as
the acid will eat holes in whatever it is on. Connect the power supply,
through the ammeter, to the electrodes and submerge the platinum ends in
the acid, the polarity on the ammeter must be observed and the bent
electrode hooked to the negative side of the power supply. Why? Adjust the
current to some convenient value (no more than 4 amps) and watch the
ammeter and try to keep the current constant throughout each trial. By
filling the graduated cylinder such that its mouth is under the surface of
the acid and pulling out the stopper with the tongs, you should get a water
filled column. Mount this securely with the clamp and support. Measure
the time necessary for collection of the given amount of gas from the
negative electrode. The surface of the acid and the water inside the
cylinder must be at the same level at the end of each trial so that you
know that you have atmospheric pressure inside. By correcting this volume
(in liters) to STP, you can find the number of molecules collected (n).
There are two electrons collected per molecule so you can determine the
charge of an electron by using e-=Q/2n where Q is the total charge, which is
obtained by multiplying the current times the time. Make several trials
and average your results. How much error would have been introduced if you
failed to correct to STP?
Reference: H&R 654, S&Z 405, M 568, S 136
* * * * * * * * * * * * * * * * * * * *
!!!! C A U T I O N !!!!* * * *!!!! W A R N I N G !!!!
READ THIS PARAGRAPH!
The voltages and currents you will be using in some of the following
experiments are dangerous!!!! DO NOT touch anything until you are sure of
what you are doing. It is very good practice to keep one hand behind your
back or in your pocket and to remove your rings and watch. You must NOT
attempt to help or give advice or even approach a group if they are using high
voltages. For the experiments using cathode ray tubes, you MUST wear safety
goggles. A long sleeved shirt or sweater should also be worn. Experiments
30, 32, 33 & 34 will all use the same power supply, therefore, once your
equipment is hooked up and checked, you should wait until the other groups are
also hooked up and checked as there will be a change in voltage whenever a
tube is turned off. Whenever you connect or disconnect your equipment, the
high voltage must be turned off. If you do this while other groups are
working on an experiment, warn them, then, when you are finished with the
wiring, reset the voltage back to where it was.
EXPERIMENT 29 - THE ELECTRIC DING-DONG
See Caution. In this experiment you will be using the 10,000 volt power
supply, the two plates on tripods and the conducting ping pong ball. Hang the
ball between the two plates from one of the hooks over the front table. The
plates should be placed parallel to each other about 4-5 cm. (plus the
diameter of the ball) apart. Attach one lead from the power supply to each
plate. Turn on the power supply and increase the voltage until the ball
starts to swing, producing a chiming. Note: It may be necessary to start the
ball by gently pushing on the string, not the ball (the ball is charged when
it is between the plates). When not taking readings, turn the power supply
down to zero, especially when doing anything near the plates. You should have
the plates just far enough apart so that the ball barely touches them and does
not bounce. The period of oscillation can then be found by timing with a
stopwatch. This is your experimental value. Knowing the mass of the ball,
its radius, the plate separation and the voltage, you can, by applying
Coloumb's law, Newton's laws and various other equations, determine the
theoretical period.
References: Most of the above
EXPERIMENT 30 - THE CATHODE RAY TUBE
See caution. By using the power supply, the control boxes and connecting
cables provided, you are to calibrate a cathode ray tube. Plug in the wires,
cables, control box and a 3BP1 tube (the number is on the tube, the first
digit is the size, in this case, a 3" tube). The neck of the tube should
light faintly. By increasing the voltage to about 500, a green spot should
appear on the screen. By turning the intensity and focus controls, you should
note and write up the effects of each on the spot. Use the portable power
supply to apply a D.C. voltage to one set of plates, measuring the deflection
of the spot and plotting the voltage vs. deflection for both + and - voltages.
Do the same for the other set of plates. Were your results exactly the same?
Why? Now use one A.C. voltage and explain any variations observed between the
deflection voltage as obtained from your previous graphs and that read from an
A.C. voltmeter (not the meter on the power supply). Repeat your measurements
for a 5BP1 and a 7JP4 tube. The group performing this experiment is
responsible for setting up and putting away the power supply and cables for
everyone using them.
References: S&Z 491
EXPERIMENT 31 - THE POTENTIOMETER
You will need the potentiometer, a galvonometer, the resistor string, the
10 volt cell, a standard cell, the VOM and the VTVM. Plug in and turn on the
VTVM so it can be warming up. Using the VOM and the VTVM and the circuit in
figure 1, measure the voltage across each of the resistors in the string as
per instructions with the string. Using the standard cell, calibrate the pot
such that the galvonometer reads zero with the pot set on the voltage given for
the standard (see figure 2). Again measure the resistor voltages with the pot
(see figure 3) being careful when connecting it so as not to damage the
galvonometer, possibly taking as an initial value that found with the VTVM.
Explain the large differences observed.
References: H&R 801, S&Z 467, M 411, S 163
EXPERIMENT 32 - THE CHARGE TO MASS RATIO OF THE ELECTRON
See caution. The equipment you will use is the 3BP1 cathode ray tube and
associated components (see experiment 30 for the approximate set up) plus the
3" solenoid. Note: You will be sharing the power supply with other groups,
therefore run your power lead from the supply, leaving the supply in a central
location. With the tube approximately centered and level in the solenoid,
obtain a green spot, rotate the apparatus or arrange a bar magnet such that
the spot is centered on the face of the tube, then defocus the spot. By
running current through the solenoid, you should notice that the spot
refocuses. By knowing the accelerating potential (V), the distance between
the screen and the anode (L), the current through the solenoid needed to
refocus the spot (i), the dimensions of the solenoid (L') and the number of
turns on the solenoid (N), you will clearly derive and use the equation to
determine e/m (=(8pV)/(B2L2) where B=loNi/L' Note: L]L'). The accelerating
potential is the voltage on the tube's power supply, not the voltage on the
power supply connected to the solenoid. Do two trials, with the second
trial finding the next higher focusing current (remember to divide this by
two since the electrons have completed two complete spirals inside the
tube).
References: H&R 835, S&Z 486, M 570, S 175
EXPERIMENT 33 - THE CHARGE TO MASS RATIO OF THE ELECTRON
See caution. Follow the procedure outlined in experiment 32, only use
the 5BP1 tube, 5" solenoid and, instead of finding the second focusing point,
do one trial using only one coil and a second using both coils in SERIES.
What additional inaccuracies are introduced using this setup as compared with
that of experiment 32?
References: H&R 835, S&Z 486, M 570, S 175
EXPERIMENT 34 - DIP ANGLE AND STRENGTH OF EARTH'S MAGNETISM
See caution. Using the 7JP4 tube and hookup as in experiment 30, orient
the tube in a north-south direction and mark the spot on the tube face, then,
using the wooden holder and, without rotating the tube, flip it completely
over (180o) along a vertical plane. You should notice that the spot
has moved to the other side of the screen. Draw a line between these two
points. Now, carefully hold the tube vertically and mark the position of the
spot on either side of the line previously drawn (you will need to rotate the
tube along the vertical axis). The ratio of the length of the line to the
distance between the second set of points is the tangent of the dip angle
(prove it). Also, using the distance between the second set of dots, you can
determine the radius of the arc of the circle described as the electrons
travel the length of the tube. (R=L2/D, where L is the distance from the
second anode to the face of the tube.) By knowing the accelerating voltage
you can calculate the velocity of the electrons and, once you derive the
proper equations, you should be able to find the horizontal intensity of the
earth's magnetic field. You will probably need to use e/m in your equations.
References: IIT lm 145, S&Z 543, M 436
EXPERIMENT 35 - DETERMINING THE INDUCTANCE OF SEVERAL COILS
By using the bridge circuit in figure 4, you will determine the
inductances of several coils. Using the VTVM, determine the D.C. resistance
of the coils by taking resistance readings on two different scales and average
these two readings. Two conditions must be met in the circuit in order to
produce a null (as straight a line as possible) on the oscilloscope. First,
the wheatstone condition must hold. (What is the wheatstone condition?)
Second, the inductive reactances must cancel (what is inductive reactance?)
which means that Lx = Ls(R1/R2). Both conditions are mutually independent
(why?) but must be met simultaneously. When adjusting the resistance boxes,
you will notice that a null cannot be achieved by changing only one resistance
but that the display will pass through a minimum. When this happens, try
adjusting one of the other boxes until it also produces a minimum. Continue
in this manner until each box has been checked several times and they are all
producing the best minimum. There is no error analysis necessary but Rx
should be determined from the wheatstone condition. Make note of Lx for each
coil as you will need this information for experiment 37.
References: IIT lm 164, H&R 870, S&Z 579, S 190
EXPERIMENT 36 - CAPACITOR DISCHARGE
Using the single capacitor with its shunt (resistor in parallel across
the terminals), the chart recorder and portable power supply, you will
determine the capacitance of this capacitor. Turn on the chart recorder (DO
NOT turn it off until you are done with the experiment) and connect the two
wires coming from the sens board to the terminals on the back of the recorder
(red to red, black to black) and the two terminals on the sens board to the
terminals on the capacitor (CAUTION: ALWAYS connect red to + on a capacitor).
Turn on the servo and, with the sens turned to zero, set the pen to zero using
the zero adjust control. Connect the power supply to the capacitor (+ to red)
and charge the capacitor by turning the power supply voltage about half way
up. Leaving the power supply as is, adjust the sens control to produce a pen
deflection slightly less than full scale and, by using the power supply
voltage, slowly move the pen slightly off of the top end of the scale. Start
the chart running at some suitable speed and disconnect the power supply
(then, AFTER you disconnect the power supply, turn it down to zero). The
chart should then begin to record the graph of a negative exponential. When
this graph falls below 5-10, you may stop. Repeat the entire experiment with
the large capacitor string. (NOTE: with the large string, you will probably
be able to let the graph run for 40-50 minutes so use a suitably slow chart
speed. At least one member of the lab group must be present to monitor the
equipment throughout the entire experiment.) From these two graphs, plot
graphs of ln (base e logarithm) of V/Vo vs. time (it should be a straight
line). The slope of this line is -1/RC where R is the shunt resistance and C
is the capacitance. You should derive this equation. Calculate C from your
graph. Also find C from the time constant of the circuit (as found from the
graph). Since the recorder and the resistors are 1%, your error should be
less than 2%. Unfortunately, the values marked on the capacitors are 100%
so no error analysis is possible except that your values will be compared
to the values found on a precision instrument. You should, however, find
the percent difference each of your values is from the actual values as
marked on the capacitors.
References: H&R 802, S&Z 589, S 179, QC 42&172
EXPERIMENT 37 - THE MUTUAL INDUCTANCE BETWEEN TWO COILS
Using the two coils whose inductance you found in experiment 35, and
the same bridge arrangement, you will attempt to measure their mutual
inductance (what's that?). Put the two coils in series, in place of the
single unknown coil of experiment 35 and set one on top of the other. By
determining the inductance of this combination, flipping one of the coils
over and determining it again, you will find that you have two different
values. This is because the total inductance is given by Lt=L1+L22M,
where M is the mutual inductance you are trying to find. In one
configuration, you were using the + and in the other, the -. Determine M
for each trial. Do these two values fall mutually within the error
predicted?
References: IIT lm 164, H&R 870, S&Z 397, S 190
EXPERIMENT 38 - LC RESONANCE
Before you come to class, look up and determine the conditions for A.C.
resonance in an LC circuit. Hook the audio oscillator, the 30 ohm resistor,
the 1 lfd capacitor and the small inductance coil in series. See figure 5.
Follow the instructions on the back of the circuit board for connecting the
chart recorder or see experiment 36 for the initial setup on the recorder.
Turn on the oscillator, chart recorder and VTVM and allow them to warm up.
Hook the VTVM across the oscillator. Calculate the resonance frequency of the
circuit (if you haven't already run a computer plot) and set the oscillator
for this frequency. Using the 5 volt A.C. scale on the VTVM, adjust the
oscillator's output to 2 volts. Adjust the sens control on the chart recorder
for a deflection of about 70. Now slowly vary the frequency 20-30hz. to
either side of this resonance point and if the recorder goes up, readjust the
sens and voltage until you get back to the original deflection. The circuit
must be allowed to stabilize for at least 10 seconds after each frequency
change. Select some chart speed and timing interval which will allow you to
produce a graph which is about the same length and frequency range as your
computer plot. After each frequency change, quickly reset the output level on
the oscillator back to 2 volts. Every 50hz or so, mark the frequency on your
chart for reference. Draw a SMOOTH curve through this set of points and
compare your results from each graph and explain any differences. Turn in both
plots.
References:H&R 952, S&Z 600, M 478, S 198
EXPERIMENT 39 - MELDE'S EXPERIMENT
See exercise 39 (the sheets with the experiment). You may duplicate
these sheets but do not write on them or take them with you as other groups
will need them. Your equipment consists of a string attached between a motor
and a mounted pulley. You should clamp the motor and pulley to the tables as
far apart as the string will allow, with 10-15cm extending beyond the pulley.
DO NOT remove or readjust anything on the motor mount or drive. Using the can
provided, add sand until a resonance point is found. This can be precisely
reached by noting that, when the resonance point is reached, the can will rise
and not drop back down. The total weight of the can, sand and string hanging
from the pulley is the tension in the string. While you are doing the three
or four segment part, you should also determine the actual speed of the motor
using the attached revolution counter and a stopwatch. You should perform the
error analysis found on the exercise sheets and answer the questions proposed.
References:IIT lm 99, H&R 463, S&Z 234, M 227, S 202
EXPERIMENT 40 - THE SPEED OF SOUND
With the circuit and equipment described in figure 7, determine the
velocity of sound for the particular day you are performing this experiment.
You should get two Lissajou figures on the scope. If you don't know what a
Lissajou figure is, it would be helpful if you did a little research before
coming to class. By adjusting the audio oscillator to 2500hz, you should get
a 5-1 pattern. By moving the microphone towards or away from the speaker, you
should be able to count the number of complete rotations that the 1-1 pattern
makes and, from this, determine the wavelength. Do this as many times as
possible for as many rotations as possible until your data looks consistent.
Average these numbers. Then, from the wave equation, calculate the actual
speed of sound. Compare your results to those obtained from an equation
taking into account the atmospheric pressure and temperature on the day you
did the experiment. Note: The audio oscillator will be producing 2500hz with
less than 1hz error if your 5-1 figure is rotating less than once per second,
which means you can achieve four place accuracy. Why do both patterns rotate
when the microphone is moved?
References: IIT lm 98(#3), H&R 500, S&Z 246, M 221, S 204
EXPERIMENT 41 - GUESS WHAT
You are to create an experiment. The experiment can be in any area of
physics and can be taken from any lab manual except this one and the one you
used in your first year, provided the equipment is available, the experiment
is good physics and can be done in 84 minutes. A finalized, brief outline
listing the type of experiment, approximate procedure to be followed and the
equipment needed must be submitted at least four school days before you plan
on performing this experiment. It is suggested that you submit your outline
as early as possible just in case some minor points need changing: i.e., new
experiment, being too dangerous, not good enough or to give your instructor
time to leave town.
References: Any or all of the above plus some.
EXPERIMENT 42 - READING THE SCALES ON A PRISM SPECTROMETER
You will be determining the apex angle of a prism and also learning to
read the vernier scales on a prism spectrometer. The prism should be
mounted such that the apex angle is in the center of the stage and
splitting the beam, with one segment reflecting off of each of the two
adjacent sides. Take a reading on one side, swing the telescope around (do
not move the stage) and take a second reading through the same window. By
subtracting the two readings, you can find the total angle, which is twice
the apex angle (prove it). Your total angle should be 120o5o and if it is
radically off, you may have gone past the 360o mark, you should check this.
The outer scale reads in half degrees (30 min) and the vernier scale reads
in one minute divisions. The angle in degrees and 30 minutes is read to
the left of the zero on the vernier, then to get minutes, you find the
vernier line that is aligned with any line on the main scale and read the
number off of the vernier, adding this to your previous reading off of the
main scale. It would be best if each member of your group read the angle
and you then had the instructor read it also, comparing these values
(readings within about 2-3 minutes should be achieved). If you have time
you may want to start (and maybe finish) experiment 46.
References: IIT lm 117
EXPERIMENT 43 - THE WAVELENGTH OF SODIUM LIGHT
Using the precision Michaelson interferometer and the sodium vapor light
source, you will determine the wavelength of yellow sodium light. Set up and
align the interferometer such that the fringes are visible. This may take
some time and playing with, but DO NOT touch the mirrors. Once fringes are
found, you should notice that, by turning the screw handle, the fringes move.
You should then take a reading and continue to turn it in the same direction,
counting at least 100 fringes. This will give you a distance reading for a
given number of wavelengths. Turn the screw in the opposite direction until
the fringes start to move and again count them and take a distance reading.
You should notice that, unless you continue in the same direction, you cannot
use the ending reading as the start of the next trial. Do this as many times
as your eyes will allow and average your results. It would probably be best
if you alternate with your lab partners so as to remain sort of sane (?) after
watching and counting the fringes several times. You may observe that, at
some positions, the fringes disappear. If this occurs, adjust the micrometer
screw to another position a centimeter or two away and start the reading over.
Each member of the lab group should do at least one trial to spread the misery
around. The ratio of measurement to table movement is 25:1 on the gray
interferometer and 50:1 on the brown one. When you are finished, be sure to
COVER the MIRRORS.
Reference: IIT lm 136
EXPERIMENT 44 - THE WAVELENGTH OF LIGHT
You should calibrate the center row of gratings on the diffraction
grating slides using the laser (wavelength=6328P). Mount the grating on the
front of the laser and project the pattern the length of the room. Using the
proper equation, you can find the slit spacing. Find the angle by measuring
the spot spacing and the distance from the grating to the spots. The beam
should hit the wall as nearly perpendicular as possible. How much error is
there in your value? After you have calibrated your gratings, use a 2-meter
meterstick, a line filament lamp and several filters and determine the average
wavelength for each filter, comparing your values with those given in a
reference for approximately the same color as that of the filter used. Use
caution when using the laser so that it does not accidentally shine into
someone's eyes.
References: IIT lm 125, H&R 1123, S&Z 672, M 524, S 233
EXPERIMENT 45 - THE INDEX OF REFRACTION OF AIR AND GAS
Using the cheap interferometer, you are to find the index of refraction
of air. You must pump the system for at least one minute after the pump stops
squeaking to insure a reasonably good vacuum. Take several readings and
compare your calculated values with the actual value. Note: Since you are
adding 1 to your value, you should subtract 1 from both the book value and
your value before finding the error. Try several more trials using gas from
the table jets. Hook up the bunsen burner and let it burn for several minutes
to bleed all of the air from the system. Pump the chamber full of a vacuum,
with the vacuum sealed in, turn on the gas and hook the tube from the gas jet
to the valve and then complete this part the same way that you did with air.
References: IIT lm 114, H&R 1014, S&Z 614, M 496, S 219
EXPERIMENT 46 - PRISM SPECTROMETER AND CAUCHY COEFFICIENTS
With the prism spectrometer used in experiment 42, you will set up
equations and find the angles of minimum deviation for four prominent spectral
lines of mercury. It is your responsibility to find out how to find the
angles of minimum deviation before you come to class. When this has been
done, take three of the wavelengths, their corresponding angles and the apex
angle and feed this data into the computer program supplied. You should
derive the equations used and explain the meaning of Cauchy's coefficients.
You should then take the fourth wavelength and substitute it into the
equations to check your derived results.
References: IIT lm 117, H&R 1032, S&Z 626, M 560, S 219
EXPERIMENT 47 - PHOTO EMISSION AND CONDUCTION
A plot of the conductivity of a photo-cell vs. wavelength of light will
be made and, you hope, explained. Connect the arc-lamp on the side table so
that it projects a spectrum along the surface of the lab tables. On the other
side of the room, set up the cell on a board and paper tape such that it can
be drawn through the spectrum by the drive motor supplied. Wire the recorder
as in figure 6, with the chart speed set at 10cm/min. The lens on the arc
lamp must be cleaned after each use. When everything is ready, strike the arc
(gently). This is done by gently turning the black knob on top of the arc-
lamp until the rods touch, then backing it off until a bright arc is obtained.
It should emit a faint, fairly constant buzzz, if it doesn't, try readjusting
it. This must be done by feel as you must not look into the arc. Do not
leave the arc on more than necessary as it gets quite hot and the lens clouds
up. By pulling out the silver knob on the end of the lamp, it should start
ticking, this is the automatic feed and will help keep the arc constant and
blow up the experiment if it is not done correctly. Mark on the plot the
colors as the cell passes each one and explain this plot.
References: H&R 1179, S&Z 724, M 571, S 237
EXPERIMENT 48 - THE SIZE OF A MOLECULE
Determine the size of a molecule and attempt to verify Avagadro's number.
It works best if a uniform, thin layer of powder is used.
References: Modern Physics Workbook l964 pgs 43&44, S&Z 350
EXPERIMENT 49 - BRAGG DIFFRACTION
Using the microwave equipment, you will determine the molecular spacing
in the simulated crystalline structure. Determine the wavelength of the
projector by setting up standing waves between the projector and a metal sheet
about 1 meter away. A diode detector is then hooked to the audio amplifier
and the wavelength measured by moving the detector along the beam, near the
metal sheet, measuring the distance between several nodes. (Why?) Once you
know the wavelength of the beam, you can use the principles of Bragg
diffraction to determine the molecular spacing. You must look up and
determine the conditions required in order to perform this experiment before
you come to class. Use the meter as your detector in the second part, the
clear plastic side is the receiver. Describe the similarities between this
method and one using X-ray diffraction, what advantages does each posses?
Hint: n may be any integral number between 0.1 and 10 and should be chosen to
produce a spacing with some nice value.
References: H&R 1140, S&Z 800
EXPERIMENT 50 - RADIOACTIVE DECAY
With cubes as simulated molecules, you will attempt to verify some of the
principles of radioactive decay. Starting with a 'no-hole' side, throw the
cubes onto a suitable surface and remove every cube whose selected side is on
top. It may be necessary to carefully move some of the cubes so they are not
stacked on top of each other. Do this again, continuing to throw and remove
them as fast as possible until less than 6 are left, keeping track of how many
are left after each throw. Repeat this entire process at least twice for the
same side. Plot the total number left for all trials vs. the throw number.
You should remember that this curve should be a smooth curve and does not need
to go through every point, just close. During the second 40 minute period, do
the same but start with a 'hole' side. How does this experiment compare with
one measuring normal radioactivity with geiger counters and other electronic
equipment? In each trial, determine the 'half-life' of your cubes in terms of
throws and, from this, find the decay constant, comparing this number with the
probability of an individual cube 'decaying'.
References: H&R 196, S&Z 869, M 19, S 242
NASTY COMMENT
Well, if you survived this far, you will probably live through most any
type of lab course. Think now, are you still sane? If so, well, at least I
tried.
BIBLIOGRAPHY
NOVEL EXPERIMENTS IN PHYSICS American Institute of Physics
1964
THE HANDBOOK OF PHYSICS AND CHEMISTRY CRC publishing Co.
1929, 1964
THE PHYSICS TEACHER American Institute of Physics
April 1968
Becker INTRODUCTION TO THEORETICAL MECHANICS
McGraw Hill Publishing Co. 1954
Cleveland et. al. IIT GENERAL PHYSICS LABORATORY MANUAL
Edwards Brothers, Inc. 1957
Williams et. al. MODERN PHYSICS
Holt, Rinehart and Winston Inc. 1968
Williams et. al. MODERN PHYSICS WORKBOOK
Holt, Rinehart and Winston Inc. 1968
Halliday & Resnick PHYSICS PARTS I&II
Addison-Wesley Publishing Co. 1966
Holton & Roller FOUNDATIONS OF MODERN PHYSICAL SCIENCE
Addison-Wesley Publishing Co. 1958
Kleppner & Ramsey QUICK CALCULUS
John Wiley & Sons Inc. 1965
McCracken A GUIDE TO FORTRAN IV PROGRAMMING
John Wiley & Sons Inc. 1965
Miller COLLEGE PHYSICS
Harcourt, Brace & World 1967
Richards et, al. MODERN COLLEGE PHYSICS
Addison-Wesley Publishing Co. 1962
Schaumn OUTLINE OF COLLEGE PHYSICS
McGraw-Hill 1961
Taffel et. al. PHYSICS LABORATORY MANUAL
Allyn & Bacon 1966
Watson TEXTBOOK OF PHYSICS
Longmans, Green & Co. 1899
ADDITIONAL REFERENCES
EXPERIMENT REFERENCES
1 IIT lm 22, H&R 48, S&Z 62, M 35, S 27, QC 138
2 IIT lm 47, H&R 48&140, S&Z 62&229, M 35&195, S 27&84
3 IIT lm 41, H&R 219, S&Z 167, S 63
4 H&R 59, S&Z 104, M 44, S 31
5 IIT lm 22, H&R 101, M 66, S 41
6 IIT lm 32, H&R 345, S&Z 218, M 187, S 183, QC 272
7 IIT lm 25, H&R 85, S&Z 83, M 58, S 35, QC 138
8 QC 9&38
9 IIT lm 109, H&R 118, S&Z 117
10 S 43
11 H&R 66, S&Z 112, M 155, S 71
12 H&R 458 (Problem 9), S&Z 207, M 260, S 94
13 IIT lm 36, H&R 320, S&Z 20, M 86, S 1, QC 25
14 IIT lm 36, H&R 320, S&Z 20, M 86, S 1, QC 25
15 IIT lm 27&45, H&R 286, S&Z 179&183, M 156&165, S 67&75
16 IIT lm 27&45, H&R 286, S&Z 179&183, M 156&165, S 67&75
17 IIT lm 27&45, H&R 286, S&Z 179&183, M 156&165, S 67&75
18 IIT lm 27&45, H&R 286, S&Z 179&183&195, M 156&165&179, S 67&75
19 H&R 433&572, S&Z 350, M 305, S 114
20 M 317, S 114
21 IIT lm 88, S&Z 310, M 292, S 124
22 IIT lm 86, H&R 563, S&Z 310, M 292, S 124
23 S&Z 285, M 460
24 IIT lm 82, H&R 554, S&Z 306, M 288, S 130
25 H&R 529, M 282
26 H&R 670, S&Z 387, M 364, S 136
27 H&R 670, S&Z 387, M 364, S 136
28 H&R 654, S&Z 405, M 568, S 136
29 Most of the above
30 S&Z 491
31 H&R 801, S&Z 467, M 411, S 163
32 H&R 835, S&Z 486, M 570, S 175
33 H&R 835, S&Z 486, M 570, S 175
34 IIT lm 145, S&Z 543, M 436
35 IIT lm 164, H&R 870, S&Z 597, S 190
36 IIT lm 160, H&R 802, S&Z 589, S 197, QC 42&172
37 IIT lm 164, H&R 870, S&Z 597, S 190
38 H&R 952, S&Z 600, M 478, S 198
39 IIT lm 99, H&R 463, S&Z 234, M 227, S 202
40 IIT lm 98 (rep. 3), H&R 500, S&Z 246, M 221, S 204
41 Any or all of the above plus some
42 IIT lm 117
43 IIT lm 136
44 IIT lm 125, H&R 1123, S&Z 672, M 524, S 233
45 IIT lm 114, H&R 1014, S&Z 614, M 496, S 219
46 IIT lm 117, H&R 1032, S&Z 626, M 560, S 219
47 H&R 1179, S&Z 724, M 571, S 237
48 S&Z 350
49 H&R 1140, S&Z 800
50 H&R 196, S&Z 879, M 19, S 242
The following abbreviations are used in the above list: IIT lm-Illinois
Institute of Technology General Physics Laboratory Manual 1956;
H&R-Halliday and Resnick 1966 (dark blue); S&Z-Richards, Sears, Wehr &
Zemansky 1962 (gray); M-Miller 1967 (green); S-Schaumns 6th ed.;
QC-Quick Calculus 1965
Return to Physics Index