(Multiple choice)

(1)

Mission Control sends a brief wake-up call to astronauts in a far away spaceship. Five seconds after the call is sent, Mission Control can hear the groans of the astronauts. How far away (at most) from the earth is the spaceship?

(a) 7.5 × 10⁸ m

(b) 15 × 10⁸ m

(c) 30 × 10⁸ m

(d) 45 × 10⁸ m

(e) The spaceship is on the moon.

(2)

A ray of light passes from air into water, striking the surface of the water with an angle of incidence of 45°. Which of the following four quantities change as the light enters the water: (1) wavelength, (2) frequency,(3) speed of propagation, (4) direction of propagation.

(a) 1 and 2 only

(b) 2, 3, and 4 only

(c) 1, 3, and 4 only

(d) 3 and 4 only

(e) 1, 2, 3, and 4

(3)

Two polarizers have their transmission axes at an angle θ. Unpolarized light of intensity I is incident upon the first polarizer. What is the intensity of the light transmitted by the second polarizer?

(a) I cos² θ

(b) (I cos² θ)/2

(c) (I cos² θ)/4

(d) I cos θ

(e) (I cos θ)/4

(f) None of the above.

(4)

Which of the following is not a phenomenon whereby polarized light can be produced from unpolarized light?

(a) Absorption

(b) Reflection

(c) Birefringence

(d) Diffraction

(e) Scattering

(5)

Light known to be polarized in the horizontal direction is incident on a polarizing sheet. It is observed that only 15.0% of the intensity of the incident light is transmitted through the sheet. What angle does the transmission axis of the sheet make with the horizontal ?

(a) 8.6^o

(b) 21^o

(c) 23^o

(d) 67^o

(e) 81^o

(6) True or false:

(a) Light and radio waves travel with the same speed through a vacuum.

(b) Most of the light incident normally on an air–glass interface is reflected.

(c) The angle of refraction of light is always less than the angle of incidence.

(d) The index of refraction of water is the same for all wavelengths in the visible spectrum.

(e) Longitudinal waves cannot be polarized.

(7)

Of the following statements about the speeds of the various colors of light in glass, which are true?

(a) All colors of light have the same speed in glass.

(b) Violet has the highest speed, red the lowest.

(c) Red has the highest speed, violet the lowest.

(d) Green has the highest speed, red and violet the lowest.

(e) Red and violet have the highest speed, green the lowest.