LIGHT HOMEWORK (CH 13 & 14)

(Do not turn in this sheet)

1.  Lasers can produce pulses of light as short as one femtosecond (1x10-15 s). How long (you know, distance in meters) is such a pulse and how many wavelengths of red light are in the pulse?

2.  Geosynchronous satellites are 36,000 km above the earth’s surface. How long does a signal take to reach such a satellite?

3.  What are the primary colors of light? What are the secondary colors and which primary colors are needed to make them?

4.  What are the primary colors of dye? What are the secondary colors of dye and what dyes are needed to make them?

5.  What is the difference between a diffuse reflection and a regular reflection?

6.  A light ray is incident on a piece of glass at an angle of 38°. What is the angle of refraction?

7.  Another light ray is incident on a diamond at 38°. What is this angle of refraction?

8.  Use the table in your book to find the speed of light in each of those media.

9.  What is total internal reflection?

10.  What is the critical angle for crown glass? What is it for diamond?

11.  What causes dispersion? What do you observe when you see dispersion?

12.  Make a sketch showing how you see a rainbow. Be sure to show the relative positions of the sun, you and the water droplets.

13.  State the Law of Reflection.

14.  State Snell’s Law.

15.  A ray of light enters a mystery material from air at an angle of 25° from the normal and bends to 10° from the normal. What is the index of refraction for the mystery material?

16.  A ray of light hits a mirror at an angle of 50.3° from the normal. What is the angle of reflection and what is the angle between the incident and reflected rays?

17.  Aquariums often have thick sides made of plastic (n=1.65). If light leaves a fish and hits the plastic with an angle of 35.0°, at what angle does the light enter the air?

18.  Find the critical angle for a diamond. (n=2.42)

19.  Just as the sun is setting you see a rainbow over your lawn when the sprinklers are on. Draw a careful diagram showing the location of the sun, rainbow and you and indicate all important angles. (Use your book for info about rainbows).

20.  A dry road is a diffuse reflector while a wet one is a regular reflector. Draw a picture and explain why a wet road appears darker under a car’s headlights than a dry one.