Lesson 6 - Curved Mirrors
by
Cynthia D'Souza

This lesson was created as a part of the SMART website and is hosted by the Illinois Institute of Technology

1 In a converging mirror, the focal plane

a is formed where all the foci are formed

b is perpendicular to the principal axis

c contains the principal axis

d all the above are correct

2 The characteristics of an image formed by a converging mirror depend on

a the size of the object

b the position of the object

c the size of the object

d all of the above are correct

3 rays from a distant object are considered to be

a diverging b converging c nearly parallel d curved

4 In a converging mirror, a ray that is parallel to the principal axis is reflected

a through the principal focus

b parallel through the principal focus

c along the same path

d through the center of curvature

5 If you looked at the moon through a reflecting telescope, the image you would see would be

a real and inverted b real and erect c virtual and inverted virtual and erect

6 In a diverging mirror the principal focus and the center of curvature are

a not located on the principal axis

b real since they are located behind the mirror

c virtual since they are located behind the mirror

d real since they are located in front of the mirror

7 If your image in a small mirror is nothing but a blur of color, you are

a between the mirror and its focal point

b at or near the focal point of the mirror

c beyond the focal point of the mirror

d none of the above is true

8 The headlights of a car uses a parabolic mirror with a light bulb located

a at the focus b beyond the focus, so that the light rays reflected will spread out a maximum amount

c at the focus d beyond the focus, so that the rays reflected will be parallel

9 A diverging mirror always produces images that are

a real, erect and smaller than the object

b virtual, erect and larger than the object

c virtual, erect, and smaller than the object

d real, inverted, and smaller than the object

10 An object is located 30.0 cm from a converging mirror with a radius of curvature of 10.0 cm. The image formed will be

a real and inverted b virtual and inverted c real and erect d virtual and erect

11 A real image is located 6.0 cm from a converging mirror with a radius of curvature of 10.0 cm. How far from the mirror is the object located?

a 40.0 cm b 30.0 cm c 20.0 cm d 10.0 cm

12 An object 4.0 cm tall, placed 30.0 cm from a converging mirror, forms a real image located 6.0 cm from the mirror. Which of the following describes the image?

a an erect image 8.0 cm high

b an inverted image 8.0 cm high

c an erect image 0.80 cm high

an inverted image 0.80 cm high

13 You have a converging mirror, a candle, and a white screen. To find the center of curvature, you move the candle and the screen until the image on the screen is

a real, inverted and smaller

b real, inverted and same size

c virtual, erect and larger

d virtual, erect and smaller

Then the object is at the center of curvature.

14 Converging mirrors can focus electromagnetic waves other than light. The world's largest radio telescope located in Puerto Rico, has a converging mirror wider than the length of three football fields. The telescope detects faint radio waves from objects in the universe.

a at the center of curvature of the mirror

b at the focal point of the mirror

c beyond the focal point and the center of curvature of the mirror

d at the vertex of the mirror

Lesson7.htm

Refraction of light

1When light passes at an angle from one medium to another that is optically denser,

a the speed of light is reduced

b the ray of light is bent away from the normal

c the incident and refracted rays are on the same side of the normal

d there is no refraction

2 The index of refraction of a material is

a the speed of light in that material

b always a value that is smaller than 1.00

c the ratio of the angle of incidence to the angle of refraction

d the ratio of the speed of light in vacuum to the speed of light in that material

3 Light passes from air into ruby (n=1.54) with an angle of incidence of 60 degrees. What is the angle of refraction in degrees?

a 34 b 56 c 18 d 10

a 34

The Production and Properties of Sound

1. The velocity of sound in air is --------- to ambient temperature at any set atmospheric pressure.

A. directly proportional   B.  indirectly proportional     C.  inversely proportional     D.  unrelated

2. If air pressure remains constant and temperature rises, the speed of sound

A.  stays the same            B.  rises                               C.   falls                               D.  varies erratically

3.A French experiment carried out in the 18th century determined the speed of sound by measuring the time, over a fixed distance, between

A.  bird calls and bird flight           B.    thunder and lightning            C.  the flash and boom of cannons        D.  telegraph signals and light flashes

4. The speed of sound at human body temperature (37o) is

`A. 310 m/s          B. 365 m/s            C. 332 m/s              D. 354 m/s`

5. During a sound check, the technician at a rock concert adjusted a circuit to hear the sound from the stage through the air at the same time he could hear it through his headphones. The afternoon temperature was 30C,  the evening performance was 13o C, and the soundboard was 200 m from the stage. How much of a delay did the technician hear at the evening performance?

A. 0.02 s                          B. 0.2 s                               C.  0.1 s                                      D.  0.6 s

6. A Concorde jet flies at Mach 1.2 at an altitude of approximately 10 km (sped of sound + 1050 km/h ), and a normal jet flies at 600 km/h. How much faster does the Concorde fly than a normal jet?

A. nearly twice as fast           B.  more than twice as fast      C. about one and one-half times as fast                       D. more than three times as fast

7.The The threshold of hearing is considered to be

A. 5 dB                        B.  50 dB                        C.  0dB                                 D.20 dB

8 The threshold of hea4ring is defined by an intensity of 10 -12 W/m 2.    A conversation has a measured intensity of 10 -5 W/m 2.         The intensity in decibels is

A. 70                             B.  24                               C. 50                                 D.  60.

9A jet airplane passing a quiet restaurant produces a sound intensity of 75 dB. The sound intensity at the restaurant is 45 dB. The motorcycle noise is roughly -----more intense than the sound in the restaurant

A. 3 times                      B.  100 times                      C.  1000 times                    D. 30 times.

10 The  ( outer ear, inner ear)

A. directs sound to the eardrum and helps determine sound direction.

B.. determines the intensity and direction of sound

C. determines the frequency and intensity of sound

D. determines the frequency and direction of sound

11. The middle ear consists of the

A. cochlea, Eustachian tube, and meatus

B. hammer, anvil and spur

C. hammer, anvil and stirrup

D. meatus, semi-circular canal, and stapes

12. The human ear is most sensitive to sounds in the range of        A.   2000-3000 Hz        B.100-250 Hz          C. 10000-20000 Hz         D. 5000- 10000 Hz

13.Because the sensitivity of the human ear varies over the audio spectrum, many sound systems----- very high and ----very low frequencies to compensate.

A. dampen, dampen                         B. amplify, amplify                    C.  dampen , amplify                            D.amplify, dampen

14. A room with a reverberation of zero is called

A. an anechoic chamber     B.  an echoic chamber          C.  an isolation booth                 D. a reverberation tank

15. The ability of waves to travel round obstacles or through small openings is  called

A. refraction                       B.   reverberation                       C,. reconstitution                          D. diffraction

16. Waves with longer wavelengths diffract---- waves with shorter wavelengths

A. less than                        B. the same amount as                C. more than                           D. they are not diffracted

17. Because lower notes are more easily diffracted by openings and objects than higher notes, it is usually -----to determine the source of ---- notes

A. harder, higher                B. harder, lower                          C. easier, lower                            D. impossible, higher

18. At night, when a layer of cool air is close to the ground and warmer air is above, sound tends to

A. refract back towards the ground         B. refract away from the ground                C. reflect back to its source                D. diffract over a wide area

19. A stone is dropped into a well that is 100 m deep. The temperature is 250 C. How much time elapses between the moment when the stone is dropped and the moment when the sound of the stone hitting the bottom is heard?

A.1.0 s                                 B. 0.5 s                                     C. 4.8 s                                                         D. 8.5 s

20. A boat race is started by a cannon blast on the shore. the ships are perpendicular to the shore where the cannon is placed. the muzzle flash cannot be seen. If the nearest ship is 0.5 km from the cannon and the farthest ship is 1.0 km from the cannon, how much sooner does the nearest ship hear the cannon, if the temperature is 15o C.

A. 3.0 s                                               B. 1.5 s                                                        C 0.75 s                                                                                    D. 2.3 s

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