Last updated: November 2, 2008
PHY 2054 Discussion – Fall ‘08
Practice Exam Problems (Chapter 22)
1.
What is the energy of a photon of frequency 5.00×10 14 Hz? (Energy of Photon)
3.31×10-47 J
2.
c. 1.33×10-48 J
a. 3.31×10 -19 J
d. 1.33×10-24 J
As the angle of incidence is increased for a ray incident on a reflecting surface, the angle between the
incident and reflected rays ultimately approaches what value? (Law of Reflection)
c. 90º
3.
b.
a. zero
b. 45º
d. 180º
A beam of light in air is incident at an angle of 30º to the surface of a rectangular block of clear
plastic (n = 1.49). If the velocity of the beam before it enters the plastic is 3.00×10 8 m/s, what is its
velocity inside the block? (Index of Refraction)
m/s
4.
a. 3.00×108 m/s
b. 1.93×108 m/s
c. 2.01×108
c. 1.35×108 m/s
A light ray passes from air through a thin plastic slab (n = 1.3) with parallel sides. If the ray in air
makes an angle of 45º with the normal after leaving the slab, what is the angle of incidence for the
ray in air as it impinges upon the other side of the slab? (Snell’s Law)
a. 33º
b. 45º
c. 67º
d.
58.5º
5.
A ray of light is incident on the mid-point of a glass prism surface at an angle of 25.0º with the
normal. For the glass, n = 1.55, and the prism apex angle is 30.0º. What is the angle of refraction as
the ray enters the air on the far side of the prism? (Light Ray through a Prism)
c. 28.4º
6.
a. 14.1º
b.
22.3º
d. 46.0º
A beam of light is incident upon a flat piece of glass (n = 1.50) at an angle of incidence of 45º. Part of
the beam is transmitted and part is reflected. What is the angle between the reflected and transmitted
rays? (Reflected & Refracted Rays)
7.
a. 28º
b. 73º
c. 107º
d. 152º
A certain kind of glass has nblue = 1.650 for blue light and nred = 1.610 for red light. If a beam of white
light (containing all colors) is incident at an angle of 30.0º, what is the angle between the red and
blue light inside the glass? (Dispersion)
8.
a. 0.22º
b. 0.45º
c. 1.90º
d. 1.81º
A ray of light travels across a liquid-to-glass interface. If the indices of refraction for the liquid and
glass are, respectively, 1.75 and 1.52, what is the critical angle at this interface? (Critical Angle)
a.
30.0º
9.
b. 52.2º
c. 60.3º
d. Critical angle does not exist.
A small underwater pool light is 1 m below the surface of a swimming pool. What is the radius of the
circle of light on the surface, from which light emerges from the water (n = 1.333)? (Total Internal
Reflection)
Answers: 1-a
a. 0.57 m b. 0.77 m c. 1.13 m d. 1.43 m
2-d
3-c
4-b
5-b
6-c
7-b
8-c
9-c