Question 1

An object is placed 15 cm in front of a diverging lens whose focal length is 12 cm.Where will the image be located (in cm)?

Accepted Answer

A) -6.7 
B) -7.2 
C) -0.15 
D) -60 
E) -5.0 
A) -6.7 
B) -7.2 
C) -0.15 
D) -60 
E) -5.0 A

Question 2

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. 
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 3

If you stand closer to a concave mirror than a distance of one focal length,the image you see is

Accepted Answer

A) real and inverted. 
B) real and upright. 
C) virtual and inverted. 
D) virtual and upright. 
E) none of the above because you do not get an image. 
A) real and inverted. 
B) real and upright. 
C) virtual and inverted. 
D) virtual and upright. 
E) none of the above because you do not get an image. D

Question 4

If a convex lens were made out of very thin clear plastic filled with air,and were then placed underwater where n = 1.33 and where the lens would have an effective index of refraction n = 1,the lens would act in the same way

Accepted Answer

A) as a concave mirror in air. 
B) as a concave lens in air. 
C) as a convex lens in air. 
D) as a flat refracting surface between water and air as seen from the water side. 
E) as the glasses worn by a farsighted person. 
A) as a concave mirror in air. 
B) as a concave lens in air. 
C) as a convex lens in air. 
D) as a flat refracting surface between water and air as seen from the water side. 
E) as the glasses worn by a farsighted person.

Question 5

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

Question 6

A clown 2 m tall looks at himself in a full-length mirror (floor-to-ceiling).Where in the mirror must he look to see his feet?

Accepted Answer

A) 1 m from the floor 
B) 50 cm from the floor 
C) 25 cm from the floor 
D) at the bottom of the mirror 
E) 1.5 m from the floor 
A) 1 m from the floor 
B) 50 cm from the floor 
C) 25 cm from the floor 
D) at the bottom of the mirror 
E) 1.5 m from the floor

Question 7

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

Question 8

A camera has a converging lens with a focal length of 56 mm.If the f-number is 2.8,what is the diameter of the lens (in mm)?

Accepted Answer

A) 10 
B) 31 
C) 0.50 
D) 20 
E) 50 
A) 10 
B) 31 
C) 0.50 
D) 20 
E) 50

Question 9

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

Question 10

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. 
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 11

A magnifying glass has a convex lens of focal length 15 cm.At what distance from a postage stamp should you hold this lens to get a magnification of +2.0?

Accepted Answer

The answer of A magnifying glass has a convex lens...

Question 12

The inhabitants of a planet in another galaxy have their eyes at the exact center of their 4.0-m long bodies.How long must a plane mirror be for such a creature to be able to see all of its body in the mirror?

Accepted Answer

A) 1.0 m 
B) 2.0 m 
C) 2.5 m 
D) 4.0 m 
E) 8.0 m 
A) 1.0 m 
B) 2.0 m 
C) 2.5 m 
D) 4.0 m 
E) 8.0 m

Question 13

A soda straw is stuck into water at an angle of 36 $\degree$ to the vertical.Looking straight down,what does the angle of the submerged portion of the straw to the vertical appear to be?

Accepted Answer

The answer of A soda straw is stuck into water...

Question 14

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

Question 15

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

Accepted Answer

A) 15 
B) 25 
C) 50 
D) 100 
E) -15 
A) 15 
B) 25 
C) 50 
D) 100 
E) -15

Question 16

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

Question 17

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

Question 18

A magician can make a candle look as if it is burning under water by focusing light from a candle flame burning in air directly on top of an underwater candle.To do this you want to use a (Hint: eliminate those that cannot work. )

Accepted Answer

A) concave mirror farther than one focal length from the burning candle. 
B) a convex mirror farther than one focal length from the burning candle. 
C) a biconcave lens farther than one focal length from the burning candle. 
D) a concave mirror closer than one focal length to the burning candle. 
E) a convex lens closer than one focal length to the burning candle. 
A) concave mirror farther than one focal length from the burning candle. 
B) a convex mirror farther than one focal length from the burning candle. 
C) a biconcave lens farther than one focal length from the burning candle. 
D) a concave mirror closer than one focal length to the burning candle. 
E) a convex lens closer than one focal length to the burning candle.

Question 19

An object is placed 15 cm in front of a concave mirror with a focal length of 30 cm.What is the magnification?

Accepted Answer

A) 1 
B) 2 
C) 1/2 
D) 1/4 
E) -2 
A) 1 
B) 2 
C) 1/2 
D) 1/4 
E) -2

Question 20

A concave mirror has a radius of curvature of 1.0 m.An object is placed 2.0 m in front of the mirror.Determine the location of the image (in cm).

Accepted Answer

A) 130 
B) 83 
C) 67 
D) 150 
E) 200 
A) 130 
B) 83 
C) 67 
D) 150 
E) 200

Exam 26: Image Formation by Mirrors and Lenses

An object is placed 15 cm in front of a diverging lens whose focal length is 12 cm.Where will the image be located (in cm)?

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

If you stand closer to a concave mirror than a distance of one focal length,the image you see is

If a convex lens were made out of very thin clear plastic filled with air,and were then placed underwater where n = 1.33 and where the lens would have an effective index of refraction n = 1,the lens would act in the same way

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

A clown 2 m tall looks at himself in a full-length mirror (floor-to-ceiling).Where in the mirror must he look to see his feet?

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. )

A camera has a converging lens with a focal length of 56 mm.If the f-number is 2.8,what is the diameter of the lens (in mm)?

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)?

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

A magnifying glass has a convex lens of focal length 15 cm.At what distance from a postage stamp should you hold this lens to get a magnification of +2.0?

The inhabitants of a planet in another galaxy have their eyes at the exact center of their 4.0-m long bodies.How long must a plane mirror be for such a creature to be able to see all of its body in the mirror?

A soda straw is stuck into water at an angle of 36 °\degree° to the vertical.Looking straight down,what does the angle of the submerged portion of the straw to the vertical appear to be?

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?

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

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?

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?

A magician can make a candle look as if it is burning under water by focusing light from a candle flame burning in air directly on top of an underwater candle.To do this you want to use a (Hint: eliminate those that cannot work. )

An object is placed 15 cm in front of a concave mirror with a focal length of 30 cm.What is the magnification?

A concave mirror has a radius of curvature of 1.0 m.An object is placed 2.0 m in front of the mirror.Determine the location of the image (in cm).

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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

A soda straw is stuck into water at an angle of 36 $\degree$ to the vertical.Looking straight down,what does the angle of the submerged portion of the straw to the vertical appear to be?