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Midterm
Name
Version B
1.
The speed of light in a particular transparent material is 2.0 X 108 m/s. What is the index of
refraction of this material? (1.5)
2.
A fiber optic cable has refractive index 1.50. The critical angle above which the light stays in the
cable is (41.8o)
3.
An object of height 1 cm is at 5 cm from a spherical convex mirror. If the image is virtual and 0.4
cm high, what is the radius of curvature of the mirror? (6.7 cm)
problem: A lens with a 6 cm focal length is placed 6 cm from a postage stamp.
Answer the following three questions about the image of the stamp:
4.
Find the distance of the image from the lens (in cm). (3 cm)
5.
The image is (a) real and upright, (b) real and inverted, (c) virtual and upright, (d) virtual and
inverted, (e) a parallel ray. (c)
6.
The length of the stamp is 1.5 inches. What is the length of the image (in inches)? (0.75 inch)
7.
The image is (a) on the same side of the lens as the stamp, (b) on the side of the lens opposite to
the stamp, (c) inside the lens, (d) on both sides of the lens. (a)
-----------------------------------8. A glass brick is submerged in water with refractive index 1.33. Light is incident on the glass at an
angle of 30o and is refracted at an angle of 27o. Find the index of refraction of the glass. (1.46)
--------------------------------9.
A candle is placed 16 cm in front of a converging lens
with a focal length of 10 cm. A second converging
lens with focal length 10 cm is placed 40 cm from the
other side of the first lens. Find the distance of the
image relative to the second lens (in cm). (40 cm)
16 cm
40 cm
10.
If a wave is described by y = .02 sin (30x – 400t) (SI
units), the wavelength of the wave is (/15 m)
11.
If a wave is described by y = .02 sin (30x – 400t) (SI units), the velocity of the wave (in m/s) is
(13.3 m/s)
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12.
The figure on the right depicts a converging
lens with an object point located X and a
focal point at F. Which of the labeled points
best represents the image point of X? (A)
A
X
B
E
F
D
13.
What power lens (in diopters) corrects
nearsighted vision with a far point of 50 cm?
(-2)
C
problem: The next 2 multiple choice questions pertain to the following situation:
A Young’s double slit experiment has the screen placed 1.6 m from the double slits where the
spacing between the two slits is 0.04 mm.
14.
The angle that locates the second-order bright fringe is 2.0º. Find the wavelength of the light.
(698 nm)
15.
Find the frequency of the light source in units of 1014 Hz. (4.3 nm)
problem: The next 4 multiple choice questions pertain to the following situation:
A soap film (part of a soap bubble) has an index of refraction of 1.333. Light of wavelength 500
nm is incident normally on it.
16.
17.
Choose the correct statement: reflections from the inner surface of the bubble undergo a phase
shift equivalent to how many wavelengths? (0)
The wavelength of the light inside the soap film is, in nm (1 nm=10-9m) (375 nm)
18.
The thinnest film that will give maximum reflection of the 500 nm light in nanometers is (94 nm)
19.
The thinnest film that will not reflect the 500 nm light in nanometers is (188 nm)
The next 4 multiple choice questions pertain to the following
Two charges, -1.3 X 106 C and +1.3 X 106 C, are separated by
a distance of 6 meters. The point P is 4 m above the midpoint.
P
20. The electric force felt by a charge of +2.0 X 106 C placed
at the point P due to the positive charge alone is with
magnitude (in N) (9.4×10-4 N)
21. Find the magnitude of the electric force on the charge at
point P due to both charges in N: (1.1×10-3)
22. The resultant electric force on the charge at point P due to
both charges is (b)
(a) directed to the left, {b) directed to the right, (c) directed upward, (d) directed downward, (e) 0
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23. Smiley Face is between two broadcasters A and B who are
18 m apart. He walks from A toward B until he receives a
maximum signal 6 m from A. Find the wavelength of the
signal in meters. (6 m)
18 m

A
6m
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The next 3 multiple choice questions pertain to the following:
Three charges are placed on the corners of an equilateral triangle as
shown in figure below.
24. What is the magnitude of the force on the 2 micro-Coulomb
charge due only to the –1C charge? (0.45 N)
25. What is the magnitude of the net force on the 2 micro-Coulomb charge? (1.2 N)
26. What is the direction of the net force on the 2 micro-Coulomb charge with respect to the
positive x-axis? (160o)
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27.
Bats can detect small objects such as insects that are approximately one wavelength in size. If bats
emit a chirp at a frequency of 60 kHz, and the speed of sound in air is 340 m/s, what is the smallest
size insect they can detect? (5.7 mm)
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B