Question 1

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

Accepted Answer

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Question 2

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

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Question 3

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

Accepted Answer

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Question 4

When you stand in front of a convex mirror, the image you see is:
A)real and inverted.
B)real and upright.
C)virtual and inverted.
D)virtual and upright.
E)real and inverted if your distance from the mirror is greater than two focal lengths.

Accepted Answer

When you stand in front of a convex mirror, the image you see is virtual (meaning it cannot be projected onto a screen) and upright. This is because the rays of light reflecting off the mirror diverge, causing the image to appear smaller than the original object and closer to the mirror than it actually is.

Question 5

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:
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.

Accepted Answer

The answer of A girl is sitting on the edge...

Question 6

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

Accepted Answer

Concave mirrors and converging lenses have a focus where parallel rays converge to a point, while convex mirrors and diverging lenses cause parallel rays to diverge. Therefore, the correct answer is only 1 and 3.

Question 7

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

Accepted Answer

For maximum magnification for a normal eye, the image should be at the near point of the eye, typically about 25 cm (or 250 mm) from the eye. The lens equation is 1/f = 1/v - 1/u, where f is the focal length, v is the image distance, and u is the object distance. For maximum magnification, v = 250 mm. The magnification (M) is given by M = v/u = h'/h, where h' is the image height and h is the object height. Rearranging the lens equation and solving for u gives u = fv/(v-f). Substituting f = 10 mm and v = 250 mm gives u ≈ 10.4 mm. The magnification is then M = 250/10.4 ≈ 24. Thus, the height of the image h' = Mh = 24 * 2 mm = 48 mm. However, since this option is not available, it seems there was a mistake in my calculation. The correct approach involves using the magnification formula directly related to the lens's ability to magnify objects for a normal eye, which typically involves considering the image formed at the near point for maximum magnification. Given the error in the initial calculation, let's correct the approach by considering the magnification formula M = -v/u, where the negative sign indicates that the image formed is inverted. For a lens to provide maximum magnification for a normal eye, the image should ideally be formed at the near point of the eye, which is generally considered to be 25 cm (or 250 mm) from the eye. The magnification is also given by the ratio of the image height to the object height (M = h'/h). Without the specific details on the calculation leading directly to the choices provided, the correct selection based on standard options would involve understanding that the magnification process depends on the object's distance from the lens and the image distance from the lens, which correlates with the eye's near point for maximum visibility.

Question 8

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

Accepted Answer

When standing closer to a concave mirror than one focal length, the image formed will be virtual and upright. This is because the light rays diverge after reflecting off the mirror and the virtual image appears to be behind the mirror.

Question 9

The inhabitants of a planet in another galaxy have their eyes at the exact centre 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)1.0 m
B)2.0 m
C)2.5 m
D)4.0 m
E)8.0 m

Accepted Answer

For a creature to see its entire body in a plane mirror, the mirror must be at least half the height of the creature. Since the creature's body is 4.0 m long, the mirror must be 2.0 m long.

Question 10

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).
A)72
B)25
C)33
D)100
E)(-33)

Accepted Answer

The power of the corrective lens needed is given by:
P = 1/f, 
where P is the power of the corrective lens (in diopters) and f is the focal length (in meters).
To make the near point normal, the corrective lens needs to have a power of:
P = 1/0.25 - 1/1.0 = 4 -1 = 3 diopters
The focal length of the corrective lens can then be calculated as:
f = 1/P = 1/3 = 0.33 meters = 33 cm (Option C).

Question 11

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)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.

Accepted Answer

A lens' behavior depends on the difference in the index of refraction between the lens material and the surrounding medium. In this case, the lens (n = 1) has a lower index of refraction than the surrounding water (n = 1.33), which would cause it to diverge light rays similar to a concave lens in air. Convex lenses converge light rays, but because the lens' refractive index is lower than the water's, it acts oppositely to its design in air, thus behaving like a concave lens.

Question 12

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

Accepted Answer

The apparent depth of an object in water is given by the formula:

apparent depth = real depth / refractive index of water

In this case, the real depth is 80 cm and the refractive index of water is 1.33. So, the apparent depth is:

apparent depth = 80 cm / 1.33 = 60 cm

Therefore, the answer is Choice B, 60.

Question 13

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

Accepted Answer

The diameter of the lens can be found by dividing the focal length by the f-number. 
Diameter = Focal length / f-number = 56 mm / 2.8 = 20 mm. 
Therefore, the diameter of the lens is 20 mm. Choice D is the correct answer.

Question 14

Which ray diagrams are correct? The three rays in each diagram are distinguished by different types of lines.Hint: Check the behaviour of each ray as it interacts with the lens. 
A)B and C
B)C and D
C)D and E
D)C and E
E)C, D and E

Accepted Answer

The answer of Which ray diagrams are correct? The three...

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:
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.

Accepted Answer

When light passes from a denser to a rarer medium, the light refracts away from the normal. In this case, light travels from a medium with refractive index n (denser) to air (rarer). Therefore, the image formed by the light rays leaving the surface of the medium is virtual and closer to the viewer than the object.

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.What is the resulting magnification of the object in this setup?
A) 
B) 
C) 
D) 
E)

Accepted Answer

The answer of An object is placed 25 cm in...

Question 17

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?  
A)(-30)
B)(-15)
C)(-23)
D)(-11)
E)(-9)

Accepted Answer

The answer of A compound microscope is made with an...

Question 18

A compound microscope is made with an objective lens (f0 = 0.900 cm) and an eyepiece (fe = 1.10 cm).The lenses are separated by a distance of 10.0 cm.What is the angular magnification? (Assume the near point is 25.0 cm.)
A)(-253)
B)(-450)
C)(-770)
D)(-980)
E)(-635)

Accepted Answer

The angular magnification (M) of a compound microscope is given by the formula: M = -(L/fo) * (25/fe), where L is the distance between the lenses. Substituting the given values: M = -(10/0.9) * (25/1.1) = -253.

Question 19

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.):
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.

Accepted Answer

The answer of A magician can make a candle look...

Question 20

Which ray diagram is correct? The three rays in each diagram are distinguished by different types of lines.Hint: Check the behaviour of each ray as it interacts with the lens. 
A)A
B)B
C)C
D)D
E)E

Accepted Answer

The answer of Which ray diagram is correct? The three...

Quiz 14: Image Formation

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.

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

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?

When you stand in front of a convex mirror, the image you see is:

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:

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 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.

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

The inhabitants of a planet in another galaxy have their eyes at the exact centre 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 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 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 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) ?

Which ray diagrams are correct? The three rays in each diagram are distinguished by different types of lines.Hint: Check the behaviour of each ray as it interacts with the lens.

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:

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?

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?

A compound microscope is made with an objective lens (f0 = 0.900 cm) and an eyepiece (fe = 1.10 cm) .The lenses are separated by a distance of 10.0 cm.What is the angular magnification? (Assume the near point is 25.0 cm.)

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.) :

Which ray diagram is correct? The three rays in each diagram are distinguished by different types of lines.Hint: Check the behaviour of each ray as it interacts with the lens.