Physics 202 MWF 10:20 Spring 2002 (Ford)
Exan III Chapts. 23--26 in Cutnell and Johnson 4e
Multiple choice questions. Circle the correct answer. No work needs to be shown and no partial credit will be given.
(3 pts) 1. You see an alien spaceship that is moving either directly toward or directly away from you. The spaceship emits light in a signal beam. The wavelength of the light emitted by the spaceship is 540 nm and the wavelength you observe the light to have is 536 nm. Is the spaceship moving toward you are away from you?
(a) toward you
(b) away from you
(3 pts) 2. In an RCL series circuit the ac voltage source has a frequency greater than the resonant frequency. The source voltage
(a) leads the current
(b) lags the current
(c) is in phase with the current
(4 pts) 3. For the circuit shown in the drawing, what is the rms current provided by the generator when the frequency of the generator is very large?
(a) 0
(b) 2.4 A
(c) 4 A
(d) 6 A
(e) 12 A
(f) infinity
(3 pts) 4. You are standing to the left of a thin lens. Your image formed by the lens is also to the left of the lens. The image is
(a) upright
(b) inverted
(c) could be either; need more information before can know
(4 pts) 5. A layer of benzene (n = 1.50) is sitting on top of water (n = 1.33). A ray of light traveling in the benzene strikes the interface between the two liquids at an angle of incidence 
1. What is the smallest value of the angle 1 for which no light will be refracted into the water?
(a) 37.8°
(b) 41.8°
(c) 48.8°
(d) 54.7°
(e) 62.5°
(f) 67.0°
(g) 90.0°
(3 pts) 6. A layer of benzene (n = 1.50) is sitting on top of water (n = 1.33). A ray of light traveling in the water is refracted into the benzene. The ray is incident on the interface between the two liquids at an angle of incidence of 20° and as it enters the benzene it is bent
(a) toward the normal
(b) away from the normal
(3 pts) 7. Two identical containers, one filled with ethyl alcohol (n = 1.36) and the other filled with benzene (n = 1.50) are viewed from directly above. Which container (if either) appears to have the greater depth of fluid?
(a) the one filled with benzene
(b) the one filled with ethyl alcohol
(c) neither; they appear the same
Show all your work. Partial credit will be given if earned. Write your answers in the blanks provided.
(14 pts) 8. A nearsighted person has a far point of 2.0 m.
a) What is the focal length of contact lenses that will allow this person to focus on distant objects?
Ans. _________________
b) Are the lenses converging or diverging?
Ans. _________________
(13 pts) 9. Unpolarized light of intensity 200 W/m2 is incident on two polarizers. The axis of the first polarizer is at an angle of 25° counterclockwise from the vertical. The axis of the second polarizer is at an angle of 62° counterclockwise from the vertical.What is the intensity of the light after it has passed through the second polarizer?
Ans. _____________
(16 pts) 10. A future space station in orbit around the earth is being powered by a beam of electromagnetic radiation sent from the surface of the earth. The beam has a uniform cross-sectional area of 200 m2 and delivers an average power of 6000 W to the space station. What is the rms value of the electric field of the beam?
Ans. ______________
(16pts) 11. A dentist's mirror is placed 20 cm from a tooth. The image formed by the mirror is upright and three times larger than the tooth.
a) Is the mirror convex, concave, or plane (flat)?
Ans. _____________________
b) What is the focal length of the mirror?
Ans. ____________________
c) Is the image real or virtual?
Ans. ________________
(18 pts) 12. A circuit consists of a resistor with R = 150 
and a capacitor with capacitance C = 5.0 × 10-6 F in series with an ac source. The rms voltage across the resistor is 40 V and the rms voltage across the capacitor is 30 V.
a) What is the rms voltage of the source?
Ans. __________________
b) What is the average power supplied by the source?
Ans. _________________
c) What is the capacitive reactance of the capacitor?
Ans. __________________
d) Does the source voltage lag or lead the current?
Ans. ________________