Deck 26: Geometrical Optics

Question 1

An object at the center of curvature of a concave mirror forms an inverted image at the center of curvature itself.

Answer 1

True

Question 2

According to Huygens' principle, each point on a wave can be considered as the source of a new wave that propagates from that point onward.

Answer 2

True

Question 3

The image formed in a plane mirror is

A) at the same distance in front of the mirror as the object is in front of the mirror.
B) at a shorter distance in front of the mirror than the distance that the object is in front of the mirror.
C) at the same distance behind the mirror as the object is in front of the mirror.
D) at a shorter distance behind the mirror than the distance the object is in front of the mirror.
E) at a larger distance behind the mirror than the distance the object is in front of the mirror.

Answer 3

at the same distance behind the mirror as the object is in front of the mirror.

Question 4

For total internal reflection to take place, light must go from a medium of lower index of refraction to a medium of higher index of refraction.

Question 5

Magnification is positive for inverted images.

Question 6

A convex lens always produces a virtual image.

Question 7

A concave lens always produces a virtual image.

Question 8

State how to draw the three rays for finding the image position due to a thin lens.

Question 9

In a concave mirror the inside of the spherical surface is the reflecting surface.

Question 10

Which of the following sets of characteristics describes the image formed by a plane mirror?

A) real and inverted
B) real and upright
C) virtual and upright
D) virtual and inverted
E) All of the previous statements can be correct.

Question 11

State how to draw the three rays for finding the image position due to a curved mirror.

Question 12

A concave mirror always produces a real image of an object placed in front of it.

Question 13

The image distance, , is positive for images in front of a mirror.

Question 14

A wave front is not a surface of constant phase within a wave.

Question 15

A concave mirror is also known as a diverging mirror.

Question 16

According to the law of reflection of light, the angle of incidence is

A) equal to the angle of reflection.
B) smaller than the angle of reflection.
C) greater than the angle of reflection.

Question 17

The reflection of light from a rough surface is called specular reflection.

Question 18

A convex mirror always produces a virtual image smaller than the object.

Question 19

When a beam of light in air is incident at an angle of incidence θ_i < 90° on a piece of glass, the angle of refraction is larger than the angle of incidence.

Question 20

The index of refraction for a given material is directly proportional to the frequency of light.

Question 21

A beam of white light goes through dispersion in a prism. The color that bends the most is

A) violet.
B) yellow.
C) red.
D) orange.
E) green.

Question 22

Which of the following is a correct statement?

A) A concave mirror always produces a real image.
B) A convex mirror always produces a virtual image.
C) A concave mirror always produces a virtual image.
D) A convex mirror always produces a real image.
E) All of the previous statements can be correct.

Question 23

A beam of light in air is incident on a glass slab at an angle of incidence < 90°. After entering the glass slab, the beam of light

A) does not change its path.
B) follows the normal to the glass slab.
C) bends away from the normal drawn at the point of contact.
D) bends closer to the normal drawn at the point of contact.

Question 24

If the magnification of a mirror is negative, which of the following is correct?

A) The image is upright and the mirror is convex.
B) The image is inverted and the mirror is convex.
C) The image is inverted and the mirror is concave.
D) All of the previous answers can be correct.
E) None of the previous answers is correct.

Question 25

An object is placed in front of a convex mirror at a distance larger than twice the focal length of the mirror. The image will appear

A) in front of the mirror.
B) inverted and reduced.
C) inverted and enlarged.
D) upright and reduced.
E) upright and enlarged.

Question 26

The principal axis is the

A) straight line drawn from the center of curvature to the mid point of the mirror.
B) straight line drawn from the center of curvature to any point of the mirror.
C) straight line drawn from the center of curvature to a point on the outer edge of the mirror.
D) straight line joining any two points on the mirror.
E) None of the other answers given is correct.

Question 27

Which one of the following is the correct number for the magnification of a plane mirror?

A) 1.0
B) 0.25
C) 0.5
D) 1.5
E) 2.0

Question 28

David stands 2.5 meters in front of a plane mirror.
(a) How far from David is David's image in the mirror?
(b) If David moves away from the mirror at 1.5 m/s, how fast are David and his image moving apart from each other?
(c) If David is 180. cm tall, how tall is his image in the mirror?

Question 29

The angle of reflection is the angle between

A) the reflected ray and the incident ray.
B) the reflected ray and the surface of the mirror.
C) the incidence ray and the surface of the mirror.
D) the reflected ray and the normal drawn at the point where this ray meets the mirror.
E) the incident ray and the normal drawn at the point where this ray meets the mirror.

Question 30

How tall must a plane mirror be in order for you to be able to see your full image in it?

A) the same height as you
B) 1/4 of your height
C) half of your height
D) 3/4 of your height
E) twice your height

Question 31

At a quiet pond with crystal clear water, you decide to fish with bow and arrow. When you aim at the fish you see, you must aim

A) closer to the surface then you perceive the fish to be.
B) directly at the fish.
C) deeper then you perceive the fish to be.
D) It depends on how large the fish is.
E) It depends on how deep the pond is.

Question 32

A beam of light that is parallel to the principal axis is incident on a convex mirror. What happens to the reflected beam of light?

A) It also is parallel to the principal axis.
B) It is perpendicular to the principal axis.
C) It appears to be coming from the focal point on the other side of the mirror.
D) It appears to be coming from the center of curvature of the mirror.
E) It appears to be coming from a point between the focal point and the center of curvature of the mirror.

Question 33

The image formed by a concave mirror when the object is placed between the mirror and the focal point has the following characteristics:

A) virtual, upright, enlarged, image distance is larger than object distance
B) virtual, upright, reduced, image distance is smaller than object distance
C) real, inverted, enlarged, image distance is larger than object distance
D) real, upright, enlarged, image distance is larger than object distance
E) virtual, inverted, reduced, image distance is smaller than object distance

Question 34

The perpendicular distance from the center of curvature to a spherical mirror is called

A) the center of curvature.
B) the radius of curvature.
C) the focal length.
D) the perpendicular axis.
E) twice the radius of curvature.

Question 35

The critical angle for a beam of light passing from water into air is 48.8°. This means that all light rays with an angle of incidence greater than this angle will be

A) absorbed.
B) totally reflected.
C) partially reflected and partially transmitted.
D) totally transmitted.
E) totally polarized.

Question 36

Select which statement is correct in describing the image formed by a thin lens of a real object placed in front of the lens.

A) If the lens is convex, the image will never be virtual.
B) If the image is real, then it is also inverted.
C) If the image is real, then it is also upright.
D) If the image is real, then it is also enlarged.

Question 37

If a lens is submerged in water, what happens to its focal length?

A) It decreases.
B) It stays the same.
C) It becomes negative.
D) It increases.

Question 38

To burn a hole in a piece of paper using light from the Sun, which mirror would work the best?

A) Plane
B) Convex
C) Concave
D) All of the given answers would work equally as well.
E) None of the given answers would burn a hole.

Question 39

A beam of light that is parallel to the principal axis is incident on a concave mirror. What happens to the reflected beam of light?

A) It also is parallel to the principal axis.
B) It is perpendicular to the principal axis.
C) It passes through the center of curvature of the mirror.
D) It passes through the focal point of the mirror.
E) It passes between the focal point and the center of curvature of the mirror.

Question 40

An object is placed in front of a convex mirror at a distance closer than the focal length of the mirror. The image will appear

A) behind the mirror.
B) upright and reduced.
C) upright and enlarged.
D) inverted and reduced.
E) inverted and enlarged.

Question 41

An object 2.0 cm tall is placed 24. cm in front of a convex mirror whose focal length is 30. cm.
(a) Where is the image formed?
(b) How tall is it?

Question 42

FIGURE 26-3 Diff: 1 Var: 1 Page Ref: Sec. 26-6
A 3.0 cm tall statue is 48. cm in front of a biconvex lens (focal length 20. cm).
(a) Is the image real or virtual?
(b) How far is the image from the lens?
(c) Is the image upright or inverted?
(d) How high is the image?

Question 43

The index of refraction for a certain material is 1.399 for red light and 1.432 for blue light. Find the angle separating the two refracted colors if the:
(a) angle of incidence is 30°.
(b) angle of incidence is 60°.

Question 44

A ray of light strikes a plane mirror perpendicular to the mirror. What is the angle of reflection?

A) 0°
B) 90°
C) 180°
D) 360°
E) 270°

Question 45

The end of a cylindrical plastic rod is polished and cut perpendicular to the axis of the cylinder. Determine the minimum index of refraction so that a light ray entering the end of the rod will always be totally internally reflected within the rod, i.e., it will never escape the rod until it comes to the other end. Assume a critical angle of 45°.

Question 46

The reflecting surfaces of two plane mirrors are perpendicular to each other. How many images of himself will a person standing at a certain distance from the intersection of these mirrors see?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 47

FIGURE 26-1
At an amusement park you stand between two plane mirrors, which intersect at an angle of 60°. You are positioned at point P in Figure 26-1. You are 1.0 m from the nearest mirror, and 15° above it. What is the distance from you to the nearest image and to the second nearest image?

Question 48

A 3.0 cm tall statue is 24. cm in front of a concave mirror. The mirror radius of curvature is 20. cm.
(a) Is the image real or virtual?
(b) How far is the image from the mirror?
(c) Is the image upright or inverted?
(d) How high is the image?

Question 49

An object is placed 15. cm from a concave mirror of focal length 20. cm. If the object is 4.0 cm tall,
(a) where is the image formed?
(b) how tall is it?

Question 50

A laser beam strikes a plane's reflecting surface with an angle of incidence of 43°. What is the angle between the incident ray and the reflected ray?

A) 43°
B) 86°
C) 45°
D) 90°
E) 0°

Question 51

A light ray enters a glass enclosed fish tank. From air it enters the glass at 20.° with respect to the surface, then emerges into the water. The index for glass is 1.50 and for water 1.33.
(a) What is the angle of refraction in the glass?
(b) What is the angle of refraction in the water?
(c) Is there any incident angle in air for which the ray will not enter the water due to total internal reflection?

Question 52

A 2.3 cm tall statue is 15. cm in front of a convex mirror. The mirror radius of curvature is 18. cm.
(a) Is the image real or virtual?
(b) How far is the image from the mirror?
(c) Is the image upright or inverted?
(d) How high is the image?

Question 53

A ray of light strikes a plane mirror perpendicular to the mirror. What is the angle of incidence?

A) 360°
B) 0°
C) 180°
D) 90°
E) 270°

Question 54

A person approaches a plane mirror at a speed of 3 m/s. How fast does he approach his image?

A) 3 m/s
B) 4 m/s
C) 5 m/s
D) 6 m/s
E) 7 m/s

Question 55

A parallel light beam containing two wavelengths, 480. nm and 700. nm, strikes a plain piece of glass at an angle of incidence of 60°. The index of refraction of the glass is 1.4830 at 480. nm and 1.4760 at 700. nm. Determine the angle between the two beams in the glass.

Question 56

An object is placed 9.5 cm from a lens of focal length 24 cm.
(a) Where is the image formed?
(b) What is the magnification?

Question 57

A mirror is rotated at an angle of 10° from its original position. How much is the rotation of the angle of reflection?

A) 10°
B) 5°
C) 15°
D) 20°
E) 40°

Question 58

A friend who is 180. cm tall stands 2.0 m from a plane wall mirror. You stand slightly behind him, 3.0 m from the wall mirror. How tall must the mirror be if you are to see all of your friend in the mirror?

Question 59

An object is located 3.8 m in front of a plane mirror. The image formed by the mirror appears to be

A) 1.9 m in front of the mirror.
B) on the mirror's surface.
C) 1.9 m behind the mirror's surface.
D) 3.8 m in front of the mirror.
E) 3.8 m behind the mirror's surface.

Question 60

A slide projector is designed with its lens 6.0 m from the screen. The projected image is 1.5 m square of a slide object 2.5 cm square.
(a) What is the object distance from the lens?
(b) What should be the lens focal length?
(c) What is the lens POWER?

Question 61

What is the critical angle for light traveling from crown glass (n = 1.52) into water (n = 1.33)?

A) 42°
B) 48°
C) 53°
D) 57°
E) 61°

Question 62

The focal length of a convex mirror is -20 cm. What is its radius of curvature?

A) -10 cm
B) 40 cm
C) -40 cm
D) -20 cm
E) 20 cm

Question 63

The focal length of a concave mirror is 20 cm. What is its radius of curvature?

A) 10 cm
B) 40 cm
C) -40 cm
D) 20 cm
E) -20 cm

Question 64

A ray of light in air enters a glass surface at right angles to the surface. What is the angle of refraction?

A) 90°
B) 180°
C) 270°
D) 360°
E) 0°

Question 65

A object is 12 cm in front of a concave mirror, and the image is 3.0 cm in front of the mirror. What is the focal length of the mirror?

A) 0.25 cm
B) 15 cm
C) 4.0 cm
D) 2.4 cm
E) 1.3 cm

Question 66

What should be the angle between the reflecting surfaces of two plane mirrors in order for every incident beam to be parallel to its reflected beam?

A) 0°
B) 30°
C) 45°
D) 60°
E) 90°

Question 67

John's face is 20 cm in front of a concave shaving mirror of focal length 30 cm. How large an image does he observe?

A) half as large as his face
B) of the same size as his face
C) twice as large as his face
D) three times as large as his face
E) four times as large as his face

Question 68

An image is 4.0 cm behind a concave mirror with focal length 5.0 cm. Where is the object?

A) 2.2 cm in front of the mirror
B) 2.2 cm behind the mirror
C) 9.0 cm in front of the mirror
D) 1.0 cm behind the mirror
E) 20 cm behind the mirror

Question 69

The index of refraction of a certain medium is 1.5. What is the speed of light in that medium?

A) 1.0 × 10⁸ m/s
B) 2.0 × 10⁸ m/s
C) 3.0 × 10⁸ m/s
D) 4.0 × 10⁸ m/s
E) 5.0 × 10⁸ m/s

Question 70

The speed of light in a certain medium is 2.2 × 10⁸ m/s. What is the index of refraction of this medium?

A) 1.0
B) 1.2
C) 1.4
D) 1.6
E) 1.8

Question 71

An object is placed 50 cm in front of a concave mirror with a focal length of 25 cm. What is the magnification?

A) -0.50
B) -1.0
C) -1.5
D) -2.0
E) -2.5

Question 72

A ray of light in air enters a glass surface at right angles to the surface. What is the angle of incidence?

A) 0°
B) 90°
C) 180°
D) 270°
E) 360°

Question 73

John's face is 20 cm in front of a concave shaving mirror. If he observes his image to be twice as big and erect, what is the focal length of the mirror?

A) 10 cm
B) 20 cm
C) 30 cm
D) 40 cm
E) 50 cm

Question 74

A concave mirror has a focal length of 20 cm. A paraxial beam of light coming from a distant object forms its image at the focal point. If a small plane mirror is placed at the center of curvature with its reflecting side facing the focal point, where is the final image?

A) 3 cm in front of the mirror
B) 40 cm in front of the mirror
C) 50 cm in front of the mirror
D) 60 cm in front of the mirror
E) 70 cm in front of the mirror

Question 75

An object 4.0 cm in height is placed 8.0 cm in front of a concave mirror with a focal length of 10.0 cm. What is the position of its image in relation to the mirror and what are its characteristics?

A) 40.0 cm on the other side of mirror, real, 6.0 times bigger
B) 10.0 cm on the other side of mirror, virtual, 10.0 times bigger
C) 18.0 cm on the same side of mirror, virtual, 2.25 times bigger
D) 10.0 cm on the same side of mirror, real, 6.0 times bigger
E) 40.0 cm on the other side of mirror, virtual, 5.0 times bigger

Question 76

Lucite has an index of refraction of 1.50. What is its critical angle of incidence?

A) 1.16°
B) 15°
C) 41.8°
D) 65.2°
E) 87.4°

Question 77

An object is placed between C and F in front of a concave mirror with a focal length of 10 cm. What is the position of its image in relation to the mirror and what are its characteristics?

A) = 10 cm, real, smaller than object
B) = 10 cm, virtual, smaller than object
C) > 20 cm, real, larger than object
D) = 20 cm, real, same size as the object
E) = 20 cm, virtual, same size as the object

Question 78

An object 2.0 cm in height is placed at the center of curvature C in front of a concave mirror. What is the height of its image?

A) -0.50 cm
B) -1.0 cm
C) -1.5 cm
D) -2.0 cm
E) -6 cm

Question 79

An object 10.0 cm in height is placed 37.0 cm in front of a concave mirror of focal length 18.5 cm. What is the height of the image?

A) -2.5 cm
B) -5.0 cm
C) -7.5 cm
D) -20.0 cm
E) -10.0 cm

Question 80

An object is placed at F in front of a concave mirror with a focal length of 10 cm. What is the position of its image in relation to the mirror and what are its characteristics?

A) = 10 cm, real, smaller than object
B) = 10 cm, virtual, smaller than object
C) = 20 cm, real, bigger than object
D) = 20 cm, virtual, bigger than object
E) = ∞, real, much bigger than the object