Chapter 11

1. A satellite is 8.7 X 10⁹ m above the Earth. How long would a radio signal take to travel to the

satellite and back? The speed of light is 3.00 X 10⁸m.

2. If we could build a spaceship that could travel at 3.0 X 10⁵ m/s (about 0.1% the speed of light),

determine how long it would take for it to travel to Proxima Centauri, which is 4.3 light-years

away. The space capsule that went to the moon traveled at 10 km/s. Calculate how long this

space craft would take to reach Proxima Centauri.

3. Find the relative index of refraction for a plastic in which light travels at the speed 2.0 X 10⁸ m/s.

4. Different colors of light have different refractive indices in crown glass. For example, violet has

a refractive index of 1.53, and red light's refractive index is 1.52. Determine the speeds of

violet and red light in crown glass.

5. A pinhole camera is 5.0 cm long, and is positioned 300 m from a building. If the image in the

camera is 3.0 cm high, how high is the building?

6. Determine the magnification when an 80 m tall building produces a 1.5 cm inverted image in a

camera.

7. A converging mirror has a focal length of 20 cm. 30 cm in front of the mirror is placed a

3.0 cm tall candle. Where is the image, and how high is the image?

8. The focal length of a converging mirror is 20 cm. Locate an object whose image in this

converging mirror is twice as tall as the object.

9. A toy soldier is placed 10 cm from a converging mirror with a focal length of 20 cm.

a) How far from the mirror is the image?

b) Determine the magnification of the soldier.

10. Often the mirrors on large trucks will be diverging mirrors. The mirror on the truck that Mary

is driving has a focal length of -60 cm. The vehicle she sees in the mirror is 1.5 m high and is

6.0 m away. Determine the size and location of the image of the vehicle.

11. The index of refraction for diamond is 2.42. Light enters from air into a diamond at an angle

of 60^o. Calculate the angle of refraction.

12. Light enters a material at an incident angle of 50^o. The angle of refraction in the material is

40^o. Determine the index of refraction of the material.

13. The absolute index of refraction for water and carbon disulfide are 1.33 and 1.63 respectively.

If light moves from water into carbon disulfide at an angle of 30^o, find the angle of refraction.

14. In passing from medium A to medium B, light bends away from the normal.

a) Does A or B have a higher index of refraction?

b) Which of A or B has a slower speed for light?

15. Explain why you must aim below a fish if you want to spear it.

16. The angle between a ray of light in air and the surface of a block of quartz the light falls on is

60^o. If the angle of refraction is 20^o, calculate the index of refraction for quartz.

17. Light is projected upwards through several layers of immiscible liquids as shown below. Note

that the angle of incidence between the glass and carbon disulfide is 10^o. At what angle will

the light emerge into the air?

18. The angle between the incident light and the surface of the equilateral glass prism is 60^o. The

absolute index of refraction of the prism is 1.51. What is the refractive angle of the ray of light

when it emerges from the prism back into the air? The diagram shows an angle labeled angle

of deviation. What is this angle?

19. A copper crown is placed on the bottom of a tub filled with water as shown below. The

refractive index for water is 1.33. A ray of light from the crown leaves the water, and just

skims by the top of the tub. The distances AB and BC are both 1.00m. Determine the depth

of the water.

20. A child at point G begins to sink in the water. A lifeguard located at L can run at 8.0 m/s and

swim at 3.0 m/s. Which route will bring the lifeguard to the child in the shortest amount of

time?

21. An engineer is late for work and is running along the road from her home at H to the office at S.

The engineer can run at 4.0 m/s on the paved road, HZ. At Y, she runs through a field with tall

grass in it. Because of the grass, she can only run at 2.0 m/s in the field. Determine the distance

Y is from H, so that the shortest time is taken in getting to work.

22. Different types of glass have different indices of refraction. One type of glass has an index of

1.53, and another has an index of 1.60. Determine if the critical angle for the glass with index

1.53 is larger or smaller than for the glass with index 1.60. Would you answer differently if the

second medium is water rather than air?

23. Explain where total internal reflection occurs in a glass fish tank. (Hint, the light must exit the

tank, and the surfaces to be considered are the water - glass surface and the glass - surface.

24. The diagram below shows light passing from water, to glass, and finally to air.

a) What is the angle of refraction in the air?

b) If the 30^o angle is increased to 52^o, what will the angle of refraction be upon emerging

from the glass?

25. Determine the critical angle if light moves from

a) glass with an index of refraction of 1.52 into air.

b) glass into water which has an index of refraction of 1.33.

26. a) Determine the critical angle for a medium with an absolute index of refraction of 1.68.

b) Calculate the absolute index of refraction for a medium with a critical angle of 40^o.

27. Where must an object be placed so that the image produced by a converging lens of focal

length 40 cm, is the same size as the object. Note that we are concerned only with real

images in this question.

28. An object is placed 30 cm in front of a converging lens of focal length 20 cm. If the object is

5.0 cm high, where is the image located, and what size is the image?

29. A screen is 7.0 cm from a converging lens with focal length 6.0 cm. If a clear image of a light

bulb is to be formed on the screen, where must the light bulb be located?

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November 22, 2013