Deck 17: Light and Image Formation

Question 1

Light from the sun passes through a converging lens and forms an image at

A) infinity.
B) the center of the lens.
C) the focal point.
D) the center of curvature of the lens.

Answer 1

the focal point.

Question 2

Which of the following lenses is a diverging lens?

A) A
B) B
C) C

Answer 2

A

Question 3

A plane mirror will always produce a

A) virtual, inverted image.
B) real, erect image.
C) virtual, erect image.
D) real, inverted image.

Answer 3

virtual, erect image.

Question 4

Convex (converging) lenses are worn by

A) a nearsighted person to make rays from a nearby object diverge less strongly.
B) a nearsighted person to make rays from a distant object diverge more strongly.
C) a farsighted person to make rays from a distant object diverge more strongly.
D) a farsighted person to make rays from a nearby object diverge less strongly.

Question 5

A rainbow shows separate colors of the spectrum because, at raindrop surfaces,

A) all colors are bent the same, hence the separation.
B) red light is bent more than green light.
C) green light is bent more than blue light.
D) blue light is bent more than red light.

Question 6

The unaided nearsighted human eye focuses light from a distant object

A) in front of the retina.
B) on the retina.
C) behind the retina.
D) acceptably but is too short for the focusing power of the cornea.

Question 7

The rearview mirror of an auto bears the legend "Objects in mirror are closer than they appear." This mirror is a ______ mirror.

A) plane
B) concave
C) convex
D) converging

Question 8

In normal use, the image seen through eyeglasses is

A) virtual.
B) real.
C) both A and B

Question 9

The cornea of the human eye is an example of a

A) converging mirror.
B) converging lens.
C) diverging lens.
D) convex mirror.

Question 10

Light is refracted as it crosses the interface between two different media because

A) it changes frequency.
B) it loses energy.
C) it changes speed.
D) it becomes polarized.

Question 11

In the primary or inner rainbow, the

A) outer edge of the bow appears red and the inner edge appears blue or violet.
B) outer edge of the bow appears blue or violet and the inner edge appears red.
C) outer edge of the bow appears yellow and the inner edge appears green.
D) pot of gold is always at the left end.

Question 12

Rays from a distant object do not diverge enough for a nearsighted person to focus; this can be corrected with a

A) diverging or positive lens.
B) diverging or negative lens.
C) converging or positive lens.
D) converging or negative lens.

Question 13

A fish looks up through the smooth surface of the water at a bear directly above it. To the fish, the bear appears to be

A) further away than it really is.
B) closer to the point directly above the fish than it really is.
C) exactly where it really is.
D) The bear cannot be seen by the fish, due to total internal reflection.

Question 14

A shaving mirror and a make-up mirror both magnify the image. Thus, these mirrors are ___________ mirrors.

A) plane
B) concave
C) convex

Question 15

When light enters a medium with a higher index of refraction it

A) is absorbed.
B) is bent away from the normal.
C) is bent towards the normal.
D) continues in the same direction.

Question 16

The image produced by a single diverging lens will ALWAYS be

A) erect and virtual.
B) erect and real.
C) at infinity.
D) inverted and virtual.
E) inverted and real.

Question 17

A ray of light moves from air into water. Which path most accurately shows the refraction?

A) A
B) B
C) C
D) D
E) E

Question 18

The focal length of a glass lens depends on

A) the curvature of the surface of the lens.
B) the index of refraction of the glass.
C) the intensity of the light passing through the lens.
D) both the index of refraction of the glass and the intensity of the light passing through the lens.
E) both the curvature of the surface of the lens and the index of refraction of the glass.

Question 19

When light is reflected from a smooth, plane mirror

A) the angle of reflection is the same as the angle of incidence.
B) the light is changed to a lower frequency.
C) most of the light is scattered into multiple directions.
D) the wave characteristics are predominant.

Question 20

A converging lens

A) always has two curved surfaces.
B) always has a real image.
C) refracts all light toward the focal point.
D) is thicker in the center than the edges.

Question 21

Light enters water (n = 1.33) from air. The incident light ray makes a 0.44 $\degree$ angle with the normal to the surface on the air side. What will be the angle made with the normal by the refracted ray on the water side?

A) nearly 90 $\degree$
B) 1.58 $\degree$
C) 0.33 $\degree$
D) 0.188 $\degree$

Question 22

A ray of light traveling through water passes through an air bubble. Which path does it take?

A) A
B) B
C) C
D) D
E) E

Question 23

Suppose a fish is observed below the surface of a lake. The distance the fish appears below the surface when looking down from above into the water (n = 1.33) is

A) greater than the fish's actual distance.
B) equal to the fish's actual distance.
C) less than the fish's actual distance.

Question 24

In order for a telescope to produce a large magnification one would select lenses of

A) short focal length for the objective and long focal length for the eyepiece.
B) short focal length for both objective and eyepiece.
C) large focal length for both objective and eyepiece.
D) large focal length for the objective and short focal length for the eyepiece.

Question 25

A 1 cm object is placed 20 cm from a lens. The lens forms a real and inverted image of size 1.5 cm. What is the focal length of the lens?

A) 8.0 cm
B) 12 cm
C) 16 cm
D) 20 cm
E) 24 cm

Question 26

A raindrop is doing its part to form a primary rainbow. Red and blue light enter near the top of the raindrop together from the sun. Both red and blue are reflected once at the back surface of the drop, but when the two rays emerge on the sunward side

A) the blue ray lies below the yellow ray and is more nearly horizontal than the yellow ray.
B) the red ray lies above the blue ray and is more nearly horizontal than the blue ray.
C) the blue ray lies above the red ray and is more nearly horizontal than the red ray.
D) none of these.

Question 27

A nearsighted person requires glasses with lenses that are

A) converging, to see distant objects.
B) converging, to see near objects.
C) diverging, to see distant objects.
D) diverging, to see near objects.

Question 28

A ray emerges from water (n = 1.33) into air. The light ray will

A) bend toward the normal on the air side.
B) bend away from the normal on the air side.
C) emerge in air at the same angle as in the water.

Question 29

A woman 1.6 m in height wants a plane mirror so that she can view her full height. The minimum vertical size of such a mirror is

A) 0.4 m.
B) 0.8 m.
C) 1.6 m.
D) 3.2 m.
E) impossible to say without knowing the viewing distance.

Question 30

The speed of light in a certain type of glass is 30% slower than the speed of light in air. What is the index of refraction for that type of plastic?

A) 1.33
B) 1.43
C) 1.5
D) 1.67

Question 31

An object is placed 10 cm in front of a concave mirror of focal length 30 cm. The image will be formed

A) 20 cm in front of the mirror.
B) 20 cm behind the mirror.
C) 15 cm in front of the mirror.
D) 15 cm behind the mirror.
E) 0.05 cm behind the mirror.

Question 32

A real image of a candle formed with a converging lens can be viewed on a screen placed

A) nowhere; that is, it can't be viewed on a screen at all.
B) at either focal point of the lens.
C) anywhere on the side of the lens from which the light emerges.
D) at a single position determined by the distance of the object and the construction of the lens.

Question 33

Which of the following optical elements used alone can produce a real image of an object?

A) Convex mirror
B) Plane mirror
C) Negative lens
D) Concave mirror
E) Prism

Question 34

If the image formed by a concave mirror is closer to the mirror than the object is, then, compared to the object, the image will be

A) smaller and inverted.
B) larger and inverted.
C) larger and erect.
D) larger and real.

Question 35

A ray of light traveling in a calm pond strikes the surface at an angle of incidence which is 2 $\degree$ larger than the critical angle. This ray will

A) be refracted away from the normal to the surface in the air.
B) undergo total internal reflection and not enter the air at all.
C) be refracted toward the normal to the surface in the air.

Question 36

One difference between a microscope and a telescope is that the image formed by the objective is

A) real for the microscope but virtual for the telescope.
B) real for both, but the image is enlarged for the microscope and reduced for the telescope.
C) real for both, but the image is reduced for the microscope and enlarged for the telescope.
D) virtual for the microscope but real for the telescope.

Question 37

A ray of light in plastic reaches the edge of the plastic. The medium surrounding the plastic is air and the angle of incidence is larger than the critical angle. What will happen?

A) The ray will refract out of the plastic, bending toward the normal line.
B) The ray will refract out of the plastic, bending away from the normal line.
C) The ray will experience total internal reflection, the angle of reflection being larger than the angle of incidence.
D) The ray will experience total internal reflection, the angle of reflection equaling the angle of incidence.
E) The ray will experience total internal reflection, the angle of reflection being smaller than the angle of incidence.

Question 38

One ray that is useful in locating the image formed by a convex mirror is the ray that is incident on the mirror in a path directed toward the focal point. This ray is reflected

A) directly back along its incident path.
B) through the center of curvature.
C) on a path tangent to the mirror.
D) on a path parallel to the mirror axis.

Question 39

The image of an object placed 20 cm in front of a concave mirror of focal length 10 cm will be

A) virtual and inverted.
B) virtual and erect.
C) real and inverted.
D) real and erect.

Question 40

An object is placed 10 cm in front of a diverging lens of focal length -15 cm. The image will be located

A) 0.167 cm in front of the lens.
B) 3.0 cm behind the lens.
C) 3.0 cm in front of the lens.
D) 6.0 cm in front of the lens.
E) 6.0 cm behind the lens.

Question 41

While looking into a mirror, you notice that the image of a tree is projected onto the back of a chair (the positions of the tree and image are shown below). You must be looking into

A) a plane mirror.
B) a convex mirror.
C) a concave mirror.
D) a negative mirror.

Question 42

A prism decomposes incident white light into its ________________ colors because of refraction.

Question 43

The focal point of a lens is determined by

A) the shape of the two surfaces of the lens.
B) the index of refraction of the lens material.
C) only the shape if you have a negative lens, otherwise only the index of refraction.
D) both shape and index of refraction.

Question 44

The image formed by a concave mirror when the object distance is greater than the focal length is always

A) real
B) right side up
C) virtual
D) at a distance greater than the focal length
Fill in the Blank Questions

Question 45

Light passing from glass into air bends _________________ (toward, away from) the normal to the surface because it is traveling ____________ (slower, faster) in the glass than in air.

Question 46

The objective lens of a high-power microscope will have a ___________ (large, short) focal length and will be a __________ (converging, diverging) lens.

Question 47

A Jurassic dinosaur is approaching your vehicle and appears in the side-view mirror. It is larger than it appears in the mirror. This means that

A) its image size is larger than what the flat rearview mirror shows.
B) its image size is smaller than what the flat rearview mirror shows.
C) it is inverted and real.
D) it is a virtual image and inverted.

Question 48

Total internal reflection can occur when a light ray moves across a boundary between different materials in which direction?

A) Parallel to the surface, but only if the ray is polarized
B) Exactly perpendicular to the surface, no matter what the indices of refraction
C) From the material with the faster speed of light, into the material with the slower speed of light
D) From a material with a slower speed of light to a material with a faster speed of light

Question 49

Parallel light incident on a positive lens will ___________ as it emerges.

Question 50

A curved mirror that cannot produce a real image of an object is ______________________.

Question 51

The image viewed in a telescope is a magnified virtual image. To achieve this, a telescope must have

A) a positive objective lens with a small focal length.
B) a positive eyepiece lens with a small focal length.
C) a negative objective lens with a large focal length.
D) a negative eyepiece lens with a large focal length.

Question 52

An iPod is 20 cm in front of a flat mirror. You see the reflected image and must refocus your eye, perhaps even take off your eyeglasses, because

A) your retina has a different curvature than the flat mirror.
B) the flat mirror replaces the object in a random direction.
C) the image is inverted but virtual.
D) the image location is 20 cm behind the mirror.

Question 53

The magnification produced by a plane mirror is ____________ (sign and magnitude).

Question 54

Two pools of water contain the same depth of water but one has a blue bottom and the other red. When looking into the pools from above,

A) the red bottom pool appears deeper.
B) the pools appear to have the same depth.
C) the blue bottom pool appears deeper.
D) it is not possible to tell which will appear deeper from this information.

Question 55

Fiber optics in a DVD player contain their light by employing total internal reflection. Designers surround the pure glass core with another type of glass, called cladding, that has a different index of refraction from the core. How should you select a cladding?

A) Cladding must have a smaller index of refraction than the core.
B) Cladding must have a larger index of refraction than the core.

Question 56

Glasses prescribed to correct a nearsighted eye will have a _______________ (sign) focal length.

Question 57

When one observes a scratch on the bottom of a block of clear plastic, the scratch appears to be 2.5 cm below the top surface as viewed from above. The actual thickness of the plastic block is 3.0 cm. The index of refraction of the block is ______________.

Question 58

Rays of light traveling through different media hit the boundary between the media and the air. The angle of incidence is the same in each case. Which medium has the largest index of refraction?

A) A
B) B
C) C
D) D

Question 59

A beam of white light in air passes through the transparent object shown. Dispersion is observed to occur. From the diagram we can tell that

A) the index of refraction is larger for red light than blue.
B) the index of refraction is larger for blue light than red.
C) the object acts as a converging lens.
D) the object behaves as a concave mirror.

Question 60

Lenses can be used to focus sunlight to a small point to burn paper or dry brush. A person demonstrates this using their own eyeglasses as the lenses. From this you can tell that

A) the person is farsighted.
B) the person is nearsighted.
C) the person is either near- or farsighted but not both.
D) the person is both near- and farsighted.

Question 61

An object is placed in front of a concave mirror. The object is farther from the mirror than the focal length of the mirror. The type of image reflected from the mirror is __________ and the orientation of the image is ___________.