Question 1

A girl is sitting on the edge of a pier with her legs dangling over the water. Her soles are 80.0 cm above the surface of the water. A boy in the water looks up at her feet and wants to touch them with a reed. (nwater = 1.333.) He will see her soles as being

Accepted Answer

A)   right at the water surface.
B)   53.3 cm above the water surface.
C)   exactly 80.0 cm above the water surface.
D)   107 cm above the water surface.
E)   an infinite distance above the water surface. D

Question 2

An object is placed 25 cm in front of a lens of focal length 20 cm. 60 cm past the first lens is a second lens of focal length 25 cm. How far past the 25 cm lens does the final image form?

Accepted Answer

A)   20 cm
B)   40 cm
C)   16 cm
D)   25 cm
E)   47 cm C

Question 3

Bottles of perfume sometimes have thick glass (n = 1.5) walls which give the impression the volume is larger than it really is. Assume a cylindrical bottle with an inner radius of 1.0 cm and an outer radius of 2.0 cm. What percentage of the apparent volume is the real volume?

Accepted Answer

A)   95%
B)   60%
C)   80%
D)   64%
E)   75% D

Question 4

An object 50-cm high is placed 1.0 m in front of a converging lens whose focal length is 1.5 m. Determine the image height (in cm).

Accepted Answer

A)   77
B)   150
C)   52
D)   17
E)   83

Question 5

A far-sighted student has a near point of 1.0 m. Calculate the focal length (in cm) of the glasses needed so the near point will be normal (25 cm).

Accepted Answer

A)   72
B)   25
C)   33
D)   100
E)   −33

Question 6

A contact lens is made of plastic with an index of refraction of 1.50. The lens has an outer radius of curvature of +2.0 cm and an inner radius of curvature of +2.5 cm. What are the focal length and the power of the lens?

Accepted Answer

The answer of A contact lens is made of plastic...

Question 7

An object is placed 25 cm in front of a lens of focal length 20 cm. 60 cm past the first lens is a second lens of focal length 25 cm. What is the resulting magnification of the object in this setup?

Accepted Answer

A)  
B)  
C)  
D)  
E)

Question 8

A plane convex lens is made of glass (n = 1.5) with one flat surface and the other having a radius of 20 cm. What is the focal length (in cm) of the lens?

Accepted Answer

A)   20
B)   30
C)   40
D)   10
E)   50

Question 9

The purpose of prescription glasses for a near-sighted person is to bring the apparent positions of distant objects

Accepted Answer

A)   to the far point of the eye
B)   to the near point of the eye
C)   to the retina of the eye
D)   none of the above

Question 10

An object 4 cm high is placed 15 cm in front of a convex mirror with a focal length of −10 cm. What is the image position (in cm)?

Accepted Answer

A)   −8
B)   −4
C)   −2
D)   −6
E)   30

Question 11

A dentist uses a concave mirror (focal length 2 cm) to examine some teeth. If the distance from the object to the mirror is 1 cm, what is the magnification of the tooth?

Accepted Answer

A)   6
B)   1
C)   4
D)   2
E)   1.5

Question 12

A compound microscope is made with an objective lens (  = 0.90 cm) and an eyepiece (  = 1.1 cm). The lenses are separated by a distance of 10 cm. If an object is 1.0 cm in front of the objective lens, where will the final image of the eyepiece be located?

Accepted Answer

A)   −30
B)   −15
C)   −23
D)   −11
E)   −9

Question 13

A telescope is constructed with two lenses separated by a distance of 25 cm. The focal length of the objective is 20 cm. The focal length of the eyepiece is 5 cm. Calculate the magnitude of the angular magnification of the telescope.

Accepted Answer

A)   6
B)   4
C)   8
D)   10
E)   5

Question 14

A convex mirror has a focal length of −20 cm. What is the position of the resulting image (in cm) if the image is upright and four times smaller than the object?

Accepted Answer

A)   −100
B)   −25
C)   −50
D)   −15
E)   −10

Question 15

The image of an object beneath the surface of a medium of refractive index n > 1 is seen in air by a person looking down on the surface. This image, formed by light rays leaving the flat refractive surface, is

Accepted Answer

A)   real and closer to the viewer than the object.
B)   virtual and closer to the viewer than the object.
C)   real and farther from the viewer than the object.
D)   virtual and farther from the viewer than the object.
E)   virtual and the same distance from the viewer as the object.

Question 16

Bottles of perfume sometimes have thick glass (n = 1.5) walls which give the impression the volume is larger than it is. Assume a cylindrical bottle has an inner radius of 1.0 cm and an outer radius of 2.0 cm. How thick (in cm) would the wall appear if you could see a mark on the inside surface?

Accepted Answer

A)   0.80
B)   0.51
C)   0.72
D)   80
E)   12

Question 17

A 10-cm focal length converging lens is used to magnify small newspaper print 2.0 mm high. Calculate the height of the image (in mm) for the maximum magnification for a normal eye.

Accepted Answer

A)   3.5
B)   7.0
C)   9.2
D)   12
E)   2.5

Question 18

An object is placed 10 cm in front of a concave mirror with a 20-cm focal length. Determine the image location (in cm).

Accepted Answer

A)   −20
B)   −15
C)   −10
D)   −5
E)   6.7

Question 19

A fish is 80 cm below the surface of a pond. What is the apparent depth (in cm) when viewed from a position almost directly above the fish? (For water, n = 1.33.)

Accepted Answer

A)   50
B)   60
C)   40
D)   70
E)   110

Question 20

A convex mirror has a focal length of −20 cm. What is the object distance if the image distance is −10 cm?

Accepted Answer

A)   10 cm
B)   40 cm
C)   60 cm
D)   20 cm
E)   30 cm

Exam 36: Image Formation

A girl is sitting on the edge of a pier with her legs dangling over the water. Her soles are 80.0 cm above the surface of the water. A boy in the water looks up at her feet and wants to touch them with a reed. (n_water = 1.333.) He will see her soles as being