SMILE Notes for 27 January 1998

Prepared by Alex Junievicz

Note: SMILE Webswingers Session: Saturday 28 February 1998, 9-11:30 am, 206 Life Sciences Building. All students and teachers are invited.

Carol Zimmerman [Lane Tech High School]

An Idea stemming from Judy Jenson. [Since the dry winter leads itself to successful experiments using static electricity, we have an adaptation of the Millikan Oil Drop Experiment.]

Equipment: 14 plastic eggs with BBs [or fishing shot] in each, 15th that is empty

Problem: Determine the mass of a single shot.

Solution: Measure their masses and arrange the masses in increasing magnitude. Determine the smallest change.

Data: [Courtesy of Fred Schaal] Masses in grams

  1. 10.9 11.7 13.2 15.1 15.7 16.9 19.3 20.3 21.8 24.1 25.9 28.8 30.1 32.0

Differences in mass [in grams]

  1. 0.8 1.5 1.9 0.6 1.2 2.4 1.0 1.5 2.3 1.8 2.9 1.3 1.9

Number of BB"s [an estimate]

0 3 4-5 7 10 11 13 17 19 21 23 25 28 33 35

Mass of a single BB is about 0.6 grams.

Comments by Ann Brandon:

Using a Histogram one could determine 1. mass of chicken

______ 2. mass of shell

X 3 eggs 3. total number of chickens

| X_______

Mass | X X 2 eggs

| X X ______

| X X X X 1 egg How? --- levels

| X X X X ___ every egg has an identical shell

|_X_X_X_X X shell egg contents 2X

|_X_X_X_X_X_______

eggs

Post session question by Porter Johnson: Robert Millikan quoted a number [with errors] for the charge of a single electron. What is our best number for the mass of a single shot, and what is its uncertainty?

Bill Blunk [Joliet Central High School]

To be effective tell a story especially one that involves the teacher in a negative.

He showed a water rocket and shot it off without the H2O showing it traveled about 15 feet. When he was in school they just introduced it. Being young he decided to challenge a friend, but they discovered a need for a change of outfits. Forgetting they were water powered. Suspect the flow of H2O has more mass than air, therefor more reactions.

Also showed the difference in burning a match and then covering the match with tin foil so that all the exhaust would go in one direction, thus creating a match rocket.

 

Alex Junievicz [CPS Substitute]

Dissection-learn what it inside electronic parts--a help in understanding what they do.

Passed out another way of looking at the color code... using the equivalent number as the number of

zero's ... Red Red Red = 2 + 2 + two zeros

 

Today the topic was inductors. He showed the basic types.

Special applications

Voltage regulators

Swinging reactors

change Inductance by change of current?

RMS vs P-P

Constant voltage transformers

Magnet amplifiers (solid state without silicon

Circulators- 3 port toroidal under magnet

field - used instead of an antenna switch in

situations to prevent intermodulation--cell phones?

Ann Brandon [Joliet Central High School]

She showed an alternate to the breakable static generation equipment.

Frey Charging Strips

#F02803 $3.85

1-800-222 FREY

She had 2 vinyl strips and 2 plastic strips

Just use paper, or Bunny Fur

Show the actions of a electroscope ( A device where there are two metals plate next to each other

and being spread apart because like charges repel.)

Charges may be transferred two ways

Conduction - where the charge directly touches

Induction - brought close to a field and then touched by ground by replacing

the charge vacated by the proximity of the altered charge of the close

field.

Ann also showed a pie plate with styrofoam cups as handles and some building insulation that also holds charges.

She showed by looking at the pie plate she could induce a charge by sliding a finger on the plate.

The most practical time for static demos is in the winter. It is dry inside in the winter because the indoor and outdoor absolute humidities are roughly equal, so that the indoor relative humidity is low.