Question 1

A concave mirror has a focal length of 20 cm.What is the position (in cm)of the object if the image is upright and is two times larger than the object?

Accepted Answer

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

Question 2

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 B

Question 3

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

Question 4

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 
A) 72 
B) 25 
C) 33 
D) 100 
E) −33

Question 5

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.

Question 6

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

Question 7

A concave mirror with a radius of curvature of 1.0 m is illuminated by a candle located on the symmetry axis 3.0 m from the mirror.Where is the image of the candle?

Accepted Answer

60 cm in f

Question 8

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

Question 9

The actual depth of a shallow pool 1.00 m deep is not the same as the apparent depth seen when you look straight down at the pool from above.How deep (in cm)will it appear to be? (nwater = 1.33. )

Accepted Answer

A) 133 
B) 75.2 
C) 90.6 
D) 117 
E) 100 
A) 133 
B) 75.2 
C) 90.6 
D) 117 
E) 100

Question 10

Of the possible statements that parallel rays are brought to a focus by a
1)
Concave mirror,
2)
Convex mirror,
3)
Converging lens,
4)
Diverging lens,
The correct answer is

Accepted Answer

A) 1 and 2. 
B) 3 and 4. 
C) 1 and 3. 
D) 2 and 3. 
E) 2 and 4. 
A) 1 and 2. 
B) 3 and 4. 
C) 1 and 3. 
D) 2 and 3. 
E) 2 and 4.

Question 11

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 12

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 13

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)    
A)    
B)    
C)    
D)    
E)

Question 14

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 15

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 16

An object 20-cm high is placed 50.0 cm in front of a lens whose focal length is 5.00 cm.Where will the image be located (in cm)?

Accepted Answer

A) 5.13 
B) 5.56 
C) 5.72 
D) 5.93 
E) 4.55 
A) 5.13 
B) 5.56 
C) 5.72 
D) 5.93 
E) 4.55

Question 17

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 18

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 19

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

+20 cm,+5.

Question 20

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

Exam 36: Image Formation

A concave mirror has a focal length of 20 cm.What is the position (in cm)of the object if the image is upright and is two times larger than the object?

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?

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).

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).

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

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

A concave mirror with a radius of curvature of 1.0 m is illuminated by a candle located on the symmetry axis 3.0 m from the mirror.Where is the image of the candle?

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?

The actual depth of a shallow pool 1.00 m deep is not the same as the apparent depth seen when you look straight down at the pool from above.How deep (in cm)will it appear to be? (nwater = 1.33. )

Of the possible statements that parallel rays are brought to a focus by a 1) Concave mirror, 2) Convex mirror, 3) Converging lens, 4) Diverging lens, The correct answer is

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

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?

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

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 20-cm high is placed 50.0 cm in front of a lens whose focal length is 5.00 cm.Where will the image be located (in cm)?

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?

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 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?

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?

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The actual depth of a shallow pool 1.00 m deep is not the same as the apparent depth seen when you look straight down at the pool from above.How deep (in cm)will it appear to be? (n_water = 1.33. )