Deck 34: Images

Question 1

Which of the following is true of all virtual images?

A)They can be seen but not photographed
B)They appear only briefly
C)They are smaller than the objects
D)They are larger than the objects
E)None of the above

Answer 1

None of the above

Question 2

A point source is to be used with a concave mirror to produce a beam of parallel light.The source should be placed:

A)as close to the mirror as possible
B)at the center of curvature
C)midway between the center of curvature and the focal point
D)midway between the center of curvature and the mirror
E)midway between the focal point and the mirror

Answer 2

midway between the center of curvature and the mirror

Question 3

The term "virtual" as applied to an image made by a mirror means that the image:

A)is on the mirror surface
B)cannot be photographed by a camera
C)is in front of the mirror
D)is the same size as the object
E)cannot be shown directly on a screen

Answer 3

cannot be shown directly on a screen

Question 4

The passenger-side rear view mirror on a car says, "Objects in the mirror may be closer than they appear".Assuming the images are not inverted, this mirror must be:

A)concave
B)plane
C)convex
D)mounted on the wrong side of the car
E)confused, as objects cannot be closer than they appear

Question 5

Real images formed by a spherical mirror are always:

A)on the side of the mirror opposite the object
B)on the same side of the mirror as the object but closer to the mirror than the object
C)on the same side of the mirror as the object but closer to the mirror than the focal point
D)on the same side of the mirror as the object but further from the mirror than the focal point
E)none of the above

Question 6

A man holds a rectangular card in front of and parallel to a plane mirror.In order for him to see the entire image of the card, the least mirror area needed is:

A)that of the whole mirror, regardless of its size
B)that of the pupil of his eye
C)one-half that of the card
D)one-fourth that of the card
E)an amount which decreases with his distance from the mirror

Question 7

Two plane mirrors make an angle of 120 $\degree$ with each other.The maximum number of images of an object placed between them is:

A)one
B)two
C)three
D)four
E)more than four

Question 8

A candle C sits between two parallel mirrors, a distance 0.2d from mirror 1.Here d is the distance between the mirrors.Multiple images of the candle appear in both mirrors.How far behind mirror 1 are the nearest three images of the candle in that mirror?

A)0.2d, 1.8d, 2.2d
B)0.2d, 2.2d, 4.2d
C)0.2d, 1.8d, 3.8d
D)0.2d, 0.8d, 1.4d
E)0.2d, 1.8d, 3.4d

Question 9

The image produced by a convex mirror of an erect object in front of the mirror is always:

A)virtual, erect, and larger than the object
B)virtual, erect, and smaller than the object
C)real, erect, and larger than the object
D)real, erect, and smaller than the object
E)none of the above

Question 10

When you stand in front of a plane mirror, your image is:

A)real, erect, and smaller than you
B)real, erect, and the same size as you
C)virtual, erect, and smaller than you
D)virtual, erect, and the same size as you
E)real, inverted, and the same size as you

Question 11

Roadway mirages are formed when:

A)the warm air above the hood of your car bends light from the sky, making the road appear wet
B)a layer of cold air above the road bends light from the sky, making it look like there is a puddle on the road
C)a layer of warm air above the road bends light from the sky, making it look like there is a puddle on the road
D)a layer of cold air above the road bends light from the road so it looks wet when it is actually dry
E)a layer of warm air above the road bends light from the road so it looks wet when it is actually dry

Question 12

A 5.0-ft woman wishes to see a full length image of herself in a plane mirror.The minimum length mirror required is:

A)2.5 ft
B)3.54 ft
C)5.0 ft
D)10 ft
E)no single answer: the farther away she stands the smaller the required mirror length

Question 13

A card marked IAHIO8 is standing upright in front of a plane mirror.Which of the following is NOT true?

A)The image is virtual
B)The image shifts its position as the observer shifts his position
C)The image appears as 8OIHAI to a person looking in the mirror
D)The image is caused mostly by specular rather than diffuse reflection
E)The image is the same size as the object

Question 14

A light bulb burns in front of the center of a 40-cm wide mirror that is hung vertically on a wall.A man walks in front of the mirror along a line that is parallel to the mirror and twice as far from it as the bulb.The greatest distance he can walk and see the image of the bulb at all times is:

A)20 cm
B)40 cm
C)60 cm
D)80 cm
E)120 cm

Question 15

An erect object is in front of a convex mirror a distance greater than the focal length.The image is:

A)real, inverted, and smaller than the object
B)virtual, inverted, and larger than the object
C)real, inverted, and larger than the object
D)virtual, erect, and smaller than the object
E)real, erect, and larger than the object

Question 16

A plane mirror is in a vertical plane and is rotating about a vertical axis at 100 rpm.A horizontal beam of light is incident on the mirror.The reflected beam will rotate at:

A)0 rpm
B)100 rpm
C)141 rpm
D)200 rpm
E)10,000 rpm

Question 17

An object is 2 m in front of a plane mirror.Its image is:

A)virtual, inverted, and 2 m behind the mirror
B)virtual, inverted, and 2 m in front of the mirror
C)virtual, erect, and 2 m in front of the mirror
D)real, erect, and 2 m behind the mirror
E)none of the above

Question 18

A virtual image is one:

A)toward which light rays converge but do not pass through
B)from which light rays diverge but do not pass through
C)from which light rays diverge as they pass through
D)toward which light rays converge and pass through
E)with a ray normal to a mirror passing through it

Question 19

A ball is held 50 cm in front of a plane mirror.The distance between the ball and its image is:

A)0 cm
B)50 cm
C)100 cm
D)150 cm
E)200 cm

Question 20

The angle between a horizontal ruler and a vertical plane mirror is 30 $\degree$ .The angle between the ruler and its image is:

A)15 $\degree$
B)30 $\degree$
C)60 $\degree$
D)90 $\degree$
E)180 $\degree$

Question 21

An erect object is located between a concave mirror and its focal point.Its image is:

A)real, erect, and larger than the object
B)real, inverted, and larger than the object
C)virtual, erect, and larger than the object
D)virtual, inverted, and larger than the object
E)virtual, erect, and smaller than the object

Question 22

A parallel beam of monochromatic light in air is incident on a plane glass surface.In the glass, the beam:

A)remains parallel
B)undergoes dispersion
C)becomes diverging
D)follows a parabolic path
E)becomes converging

Question 23

The focal length of a spherical mirror is N times its radius of curvature where N is:

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

Question 24

A concave refracting surface of a medium with index of refraction n produces a real image no matter where an object is placed outside:

A)always
B)only if the index of refraction of the surrounding medium is less than n
C)only if the index of refraction of the surrounding medium is greater than n
D)never
E)none of the above

Question 25

A concave spherical mirror has a focal length of 12 cm.If an erect object is placed 6 cm in front of it:

A)the magnification is 2 and the image is erect
B)the magnification is 2 and the image is inverted
C)the magnification is 0.67 and the image is erect
D)the magnification is 0.67 and the image is inverted
E)the magnification is 0.5 and the image is erect

Question 26

A man stands with his nose 8 cm from a concave shaving mirror of radius 32 cm.The distance from the mirror to the image of his nose is:

A)8 cm
B)12 cm
C)16 cm
D)24 cm
E)32 cm

Question 27

A convex spherical mirror has a focal length of 12 cm.If an object is placed 6 cm in front of it the image position is:

A)4 cm behind the mirror
B)4 cm in front of the mirror
C)12 cm behind the mirror
D)12 cm in front of the mirror
E)at infinity

Question 28

If the image distance is negative,

A)the image is real.
B)the image is virtual.
C)the mirror is concave.
D)you have made a mistake; image distances must be positive.
E)the object distance must also be negative.

Question 29

A concave refracting surface is one with a center of curvature:

A)to the left of the surface
B)to the right of the surface
C)on the side of the incident light
D)on the side of the refracted light
E)on the side with the higher index of refraction

Question 30

As an object is moved from a distant location toward the center of curvature of a concave mirror its image:

A)remains virtual and becomes smaller
B)remains virtual and becomes larger
C)remains real and becomes smaller
D)remains real and becomes larger
E)changes from real to virtual

Question 31

The image of an erect candle, formed using a convex mirror, is always:

A)virtual, inverted, and smaller than the candle
B)virtual, inverted, and larger than the candle
C)virtual, erect, and larger than the candle
D)virtual, erect, and smaller than the candle
E)real, erect, and smaller than the candle

Question 32

A concave spherical mirror has a focal length of 12 cm.If an object is placed 18 cm in front of it the image position is:

A)7.2 cm behind the mirror
B)7.2 cm in front of the mirror
C)36 cm behind the mirror
D)36 cm in front of the mirror
E)at infinity

Question 33

The figure shows a concave mirror with a small object located at the point marked 6.If the image is also at this point, then the center of curvature of the mirror is at the point marked:

A)3
B)4
C)6
D)9
E)12

Question 34

As an object is moved from the center of curvature of a concave mirror toward its focal point its image:

A)remains virtual and becomes larger
B)remains virtual and becomes smaller
C)remains real and becomes larger
D)remains real and becomes smaller
E)remains real and approaches the same size as the object

Question 35

A convex spherical surface with radius r separates a medium with index of refraction 2 from air.As an object in air is moved toward the surface from far away along the central axis, its image:

A)changes from virtual to real when it is a distance r/2 from the surface
B)changes from virtual to real when it is a distance r from the surface
C)changes from real to virtual when it is a distance r/2 from the surface
D)changes from real to virtual when it is a distance r from the surface
E)remains real

Question 36

An object O, in air, is in front of the concave spherical refracting surface of a piece of glass.Which of the general situations depicted below is like this situation?

A)I
B)II
C)III
D)IV
E)V

Question 37

A concave spherical mirror has a focal length of 12 cm.If an object is placed 6 cm in front of it the image position is:

A)4 cm behind the mirror
B)4 cm in front of the mirror
C)12 cm behind the mirror
D)12 cm in front of the mirror
E)at infinity

Question 38

A concave mirror forms a real image which is twice the size of the object.If the object is 20 cm from the mirror, the radius of curvature of the mirror must be about:

A)13 cm
B)20 cm
C)27 cm
D)40 cm
E)80 cm

Question 39

An erect object is located on the central axis of a spherical mirror.The magnification is -3.This means its image is:

A)real, inverted, and on the same side of the mirror
B)virtual, erect, and on the opposite side of the mirror
C)real, erect, and on the same side of the mirror
D)real, inverted, and on the opposite side of the mirror
E)virtual, inverted, and on the opposite side of the mirror

Question 40

At what distance in front of a concave mirror must an object be placed so that the image and object are the same size?

A)one focal length
B)half the focal length
C)twice the focal length
D)less than half the focal length
E)more than twice the focal length

Question 41

An object faces a spherical refracting surface.If r is negative,

A)the surface is convex.
B)the surface is concave.
C)the image must be real.
D)the object distance must be negative.
E)this cannot happen; r must be positive.

Question 42

Which of the following five glass lenses is a diverging lens?

A)I
B)II
C)III
D)IV
E)V

Question 43

A convex refracting surface has a radius of 12 cm.Light is incident in air (n = 1)and refracted into a medium with an index of refraction of 2.Light incident parallel to the central axis is focused at a point:

A)3 cm from the surface
B)6 cm from the surface
C)12 cm from the surface
D)18 cm from the surface
E)24 cm from the surface

Question 44

When a single-lens camera is focused on a distant object, the lens-to-film distance is found to be 40.0 mm.To focus on an object 0.540 m in front of the lens, the film-to-lens distance should be:

A)36.8 mm
B)37.3 mm
C)40.0 mm
D)42.7 mm
E)43.2 mm

Question 45

Let p denote the object-lens distance and i the image-lens distance.The image produced by a lens of focal length f has a height that can be obtained from the object height by multiplying it by:

A)p/i
B)i/p
C)f/p
D)f/i
E)i/f

Question 46

A convex refracting surface has a radius of 12 cm.Light is incident in air (n = 1)and refracted into a medium with an index of refraction of 2.To obtain light with rays parallel to the central axis after refraction a point source should be placed on the axis:

A)3 cm from the surface
B)6 cm from the surface
C)12 cm from the surface
D)18 cm from the surface
E)24 cm from the surface

Question 47

A camera with a lens of focal length 6.0 cm takes a picture of a 1.4-m man standing 11 m away.The height of the image is about:

A)0.39 cm
B)0.77 cm
C)1.5 cm
D)3.0 cm
E)6.0 cm

Question 48

A 3-cm high object is in front of a thin lens.The object distance is 4 cm and the image distance is -8 cm.The image height is:

A)0.5 cm
B)1 cm
C)1.5 cm
D)6 cm
E)24 cm

Question 49

If the image distance is negative,

A)the image is real.
B)the image is virtual.
C)the lens is converging.
D)the object distance must also be negative.
E)this is not possible; the image distance must be positive.

Question 50

An object is 30 cm in front of a converging lens of focal length 10 cm.The image is:

A)real and larger than the object
B)real and the same size than the object
C)real and smaller than the object
D)virtual and the same size than the object
E)virtual and smaller than the object

Question 51

An erect object placed outside the focal point of a converging lens will produce an image that is:

A)erect and virtual
B)inverted and virtual
C)erect and real
D)inverted and real
E)impossible to locate

Question 52

Where must an object be placed in front of a converging lens in order to obtain a virtual image?

A)At the focal point
B)At twice the distance to the focal point
C)Anywhere beyond the focal point
D)Between the focal point and the lens
E)Between the focal point and twice the distance to the focal point

Question 53

In a cinema, a picture 2.5 cm wide on the film is projected to an image 3.0 m wide on a screen which is 18 m away.The focal length of the lens is about:

A)7.5 cm
B)10 cm
C)12.5 cm
D)15 cm
E)20 cm

Question 54

A concave spherical surface with radius r separates a medium with index of refraction 2 from air.As an object in air is moved toward the surface from far away along the central axis, its image:

A)changes from virtual to real when it is a distance r/2 from the surface
B)changes from virtual to real when it is a distance 2r from the surface
C)changes from real to virtual when it is a distance r/2 from the surface
D)changes from real to virtual when it is a distance 2r from the surface
E)remains virtual

Question 55

The bellows of an adjustable camera can be extended so that the largest film to lens distance is one and one-half times the focal length.If the focal length is 12 cm, the nearest object which can be sharply focused on the film must be what distance from the lens?

A)12 cm
B)24 cm
C)36 cm
D)48 cm
E)72 cm

Question 56

An erect object is placed on the central axis of a thin lens, further from the lens than the magnitude of its focal length.The magnification is +0.4.This means:

A)the image is real and erect and the lens is a converging lens
B)the image is real and inverted and the lens is a converging lens
C)the image is virtual and erect, and the lens is a diverging lens
D)the image is virtual and erect, and the lens is a converging lens
E)the image is virtual and inverted and the lens is a diverging lens

Question 57

An object is in front of a converging lens, at a distance less than the focal length from the lens.Its image is:

A)virtual and larger than the object
B)real and smaller than the object
C)virtual and smaller than the object
D)real and larger than the object
E)virtual and the same size as the object

Question 58

A convex spherical refracting surface separates a medium with index of refraction 2 from air.The image of an object outside the surface is real:

A)always
B)never
C)only if it is close to the surface
D)only if its distance from the surface is large compared to the radius of curvature
E)only if the radius of curvature is small

Question 59

Which type(s)of lenses can produce both real and virtual images?

A)only diverging lenses
B)only converging lenses
C)only plane lenses
D)both converging and diverging lenses
E)neither converging nor diverging lenses

Question 60

A hollow lens is made of thin glass as shown.It can be filled with air, water (n = 1.3)or CS₂ (carbon disulfide, n = 1.6).A beam of parallel light entering the lens will diverge if the lens is filled with:

A)air and immersed in air
B)air and immersed in water
C)water and immersed in CS₂
D)CS₂ and immersed in water
E)CS₂ and immersed in CS₂

Question 61

A plano-convex glass (n = 1.5)lens has a curved side whose radius is 50 cm.If the image size is to be the same as the object size, the object should be placed at a distance from the lens of:

A)50 cm
B)100 cm
C)200 cm
D)340 cm
E)400 cm

Question 62

Which of the following is NOT correct for a simple magnifying glass?

A)the image is virtual
B)the image is erect
C)the image is larger than the object
D)the object is inside the focal point
E)the lens is diverging

Question 63

A converging lens of focal length 20 cm is placed in contact with, and to the left of, a diverging lens of focal length 30 cm.If an object is placed 40 cm to the left of the converging lens, the total magnification is:

A)-3.0
B)-1.5
C)-1.0
D)2.0
E)3.0

Question 64

An ordinary magnifying glass in front of an erect object produces an image that is:

A)real and erect
B)real and inverted
C)virtual and inverted
D)virtual and erect
E)none of these

Question 65

In a two lens microscope, the intermediate image is:

A)virtual, erect and magnified
B)real, erect and magnified
C)real, inverted and magnified
D)virtual, inverted and reduced
E)virtual, inverted and magnified

Question 66

A converging lens of focal length 20 cm is placed in contact with a diverging lens of focal length 30 cm.The focal length of this combination is:

A)+60 cm
B)+25 cm
C)+12 cm
D)+10 cm
E)-10 cm

Question 67

Let f_o and f_e be the focal lengths of the objective and eyepiece of a compound microscope.In ordinary use, the object:

A)is less than f_o from the objective lens
B)is more that f_o from the objective
C)produces an intermediate image which is slightly more than f_e from the eyepiece
D)produces an intermediate image which is 2f_e away from the eyepiece
E)produces an intermediate image which is less than f_o from the objective

Question 68

The object-lens distance for a certain converging lens is 400 mm.The image is three times the size of the object.To make the image five times the size of the object, the object-lens distance must be changed to:

A)360 mm
B)540 mm
C)600 mm
D)720 mm
E)960 mm

Question 69

Consider the following four statements concerning a compound microscope: Which two of the four statements are correct?

A)I, II
B)I, III
C)I, IV
D)II, III
E)II, IV

Question 70

A magnifying glass has a focal length of 15 cm.If the near point of the eye is 25 cm from the eye the angular magnification of the glass is about:

A)0.067
B)0.33
C)0.5
D)0.67
E)1.7

Question 71

The objective lens of the Yerkes telescope (the largest functioning refracting telescope in the world)has a focal length of 19.4 m.If its eyepiece has a focal length of 2.5 cm, what is the magnitude of its magnification?

A)7.8
B)13
C)130
D)780
E)cannot be calculated without knowing the length of the telescope

Question 72

The Sun subtends 0.5 $\degree$ as seen from the Earth.Its image, using a 1.0-m focal length lens, is about:

A)10 cm
B)2 cm
C)1 cm
D)5 mm
E)1 mm

Question 73

An erect object is 2f in front of a convex lens of focal length f.The image is:

A)real, inverted, magnified
B)real, erect, same size
C)real, inverted, same size
D)virtual, inverted, reduced
E)real, inverted, reduced

Question 74

Which instrument uses a single converging lens with the object placed just inside the focal point?

A)Camera
B)Compound microscope
C)Magnifying glass
D)Overhead projector
E)Telescope

Question 75

Two thin lenses (focal lengths f₁ and f₂)are in contact.Their equivalent focal length is:

A)f₁ + f₂
B)f₁f₂/(f₁ + f₂)
C)1/f₁ + 1/f₂
D)f₁ - f₂
E)f₁(f₁ - f₂)/f₂

Question 76

A converging lens is symmetric; its curved sides have radii of 50 cm.If the focal length is to be 80 cm, what should the index of refraction be?

A)0
B)0.3
C)0.6
D)1.3
E)1.6

Question 77

An object is 20 cm to the left of a lens of focal length +10 cm.A second lens, of focal length +12.5 cm, is 30 cm to the right of the first lens.The distance between the original object and the final image is:

A)0 cm
B)28 cm
C)50 cm
D)100 cm
E)infinite

Question 78

The two lenses shown are illuminated by a beam of parallel light from the left.Lens B is then moved slowly toward lens A.The beam emerging from lens B is:

A)initially parallel and then diverging
B)always diverging
C)initially converging and finally parallel
D)always parallel
E)initially converging and finally diverging