Question 1

A farsighted eye requires a 2.0-diopter lens to read comfortably from a book (held 25 cm in front of the eyes). The near point of the eye without the lens is

Accepted Answer

A)   +0.400 diopters.
B)   +2.50 diopters.
C)   -2.50 diopters.
D)   -0.400 diopters. D

Question 2

A concave mirror with a radius of 20 cm creates an image at infinity. The object was placed

Accepted Answer

A)   40 cm in front of the mirror.
B)   20 cm in front of the mirror.
C)   10 cm in front of the mirror.
D)   at infinity in front of the mirror.
E)   at infinity behind the mirror. C

Question 3

The image seen in a plane mirror is

Accepted Answer

A)   real and upright, and left and right are interchanged.
B)   real and inverted, and left and right are not interchanged.
C)   virtual and upright, and left and right are interchanged.
D)   virtual and inverted, and left and right are not interchanged.
E)   virtual and inverted, and left and right are interchanged. C

Question 4

An object is placed 20 cm in front of a convex mirror of radius 20 cm. The image is

Accepted Answer

A)   real, upright, and as large as the object.
B)   virtual, upright, and as large as the object.
C)   real, inverted, and as large as the object.
D)   virtual, inverted, and as large as the object.
E)   virtual, inverted, and larger than the object.

Question 5

A fish is 50.0 cm below the surface of a pond (index of refraction for water is 1.33). For a viewer directly above the fish, the fish appears to be placed

Accepted Answer

A)   37.6 cm below the surface of the pond.
B)   50.0 cm below the surface of the pond.
C)   66.5 cm below the surface of the pond.
D)   None of the above is correct.

Question 6

When a plano-concave lens made of glass (index of refraction 1.65) is placed in water (index of refraction 1.33), its focal length

Accepted Answer

A)   increases.
B)   decreases.
C)   stays the same.
D)   becomes zero.

Question 7

In nearsightedness, the rays passing through the eye converge before they reach the retina. To correct this, all of the following are valid (although not necessarily practical) means except for

Accepted Answer

A)   inserting a negative lens in front of the eye.
B)   relaxing the muscles that control the shape of the crystalline lens of the eye so that the lens flattens somewhat.
C)   decreasing the index of refraction of the cornea and aqueous humor that covers the crystalline lens of the eye.
D)   All of the above are true.

Question 8

If a material has an index of refraction of 1.33, the speed of light through it is

Accepted Answer

A)   1.70 * 108 m/s.
B)   2.26* 108 m/s.
C)   3.00 * 108 m/s.
D)   3.99* 108 m/s.
E)   5.30* 108 m/s.

Question 9

The color humans perceive depends primarily on the property of light we call

Accepted Answer

A)   frequency.
B)   speed.
C)   wavelength.
D)   All of the previous responses are correct.
E)   None of the previous responses is correct.

Question 10

Total internal reflection occurs from an interface when the ray is incident

Accepted Answer

A)   from a less dense medium.
B)   from a denser medium.
C)   Either of the first two responses can be valid.
D)   Total internal reflection does not depend on the density of the medium.

Question 11

Light travels fastest

Accepted Answer

A)   in a vacuum.
B)   through water.
C)   through oil.
D)   through diamond.
E)   through glass.

Question 12

A small object is placed 12 cm in front of a diverging lens with a focal length of 3.0 cm. The image will be

Accepted Answer

A)   real and inverted.
B)   real and upright.
C)   virtual and inverted.
D)   virtual and upright.

Question 13

A 2.00-m-tall clown looks at himself in a full-length (floor-to-ceiling) mirror. The image of his feet is placed

Accepted Answer

A)   at the bottom of the mirror.
B)   0.250 m above the floor.
C)   0.500 m above the floor.
D)   1.00 m above the floor.
E)   1.50 m above the floor.

Question 14

If the angle of incidence were not equal to the angle of reflection, the distance traveled by a light ray going on a path composed of two straight-line segments intersecting at the reflecting surface would be

Accepted Answer

A)   greater than it is for the actual path.
B)   the same as the actual path.
C)   less than it is for the actual path.
D)   Any on the above answers may be valid, depending on further geometric details.

Question 15

The image of a flower on a 35-mm color slide is 2.00 mm high. It is to be projected onto a screen 5.00 m from the slide, and it is to appear 50.0 cm high. The focal length of the lens used is

Accepted Answer

A)   1.99 m.
B)   2.00 m.
C)   2.01 m.
D)   502 m.
E)   498 m.

Question 16

A diver shines an underwater searchlight at the surface of the water (index of refraction 1.33) from below. The incident angle (relative to the surface of the water) for which the light will be totally reflected is

Accepted Answer

A)   41o.
B)   21o.
C)   11o.
D)   All of the above are correct.
E)   None of the above is correct.

Question 17

A diver swimming below the surface of a pond (index of refraction for water is 1.33) watches a light placed directly above his head, 50 cm above the water surface. The light appears to be placed

Accepted Answer

A)   37.6 cm above the surface of the pond.
B)   50.0 cm above the surface of the pond.
C)   66.5 cm above the surface of the pond.
D)   None of the above is correct.

Question 18

Two converging lenses of focal lengths 100 cm and 10 cm are combined to form an astronomical telescope. Its magnification is

Accepted Answer

A)   8.0.
B)   9.0.
C)   10.
D)   11.
E)   12.

Question 19

Suppose the Earth's atmosphere can be modeled by a series of cells of air with spherically shaped interfaces and indexes of refraction increasing with depth below the "top" (upper) surface. A ray strikes the upper surface at some nonzero angle with respect to the surface normal. As it comes toward the Earth, the ray direction will cause

Accepted Answer

A)   a more drastic curvature than a flat interface.
B)   a less drastic curvature than a flat interface.
C)   no change from the curvature produced by a flat interface.
D)   None of the previous responses is correct.
E)   More information is needed to work out the answer.

Question 20

The radius of curvature of a plano-convex lens made of glass (index of refraction 1.65) is 25 cm. The lens is

Accepted Answer

A)   diverging, and its focal length is 38 cm.
B)   diverging, and its focal length is 25 cm.
C)   diverging, and its focal length is 15 cm.
D)   converging, and its focal length is 25 cm.
E)   converging, and its focal length is 38 cm.

Exam 34: Reflection, Refraction, and Optics

A farsighted eye requires a 2.0-diopter lens to read comfortably from a book (held 25 cm in front of the eyes) . The near point of the eye without the lens is