CH. 23

A convex lens has focal length f. If an object is placed at a distance of 2f from the lens on the principal axis, the image is located at a distance from the lens A) of 2f. B) between f and 2f. C) of f. D) between the lens and f. E) of infinity.

A

If a object is placed between a convex lens and its focal point, the image formed is A) virtual and upright. B) virtual and inverted. C) real and upright. D) real and inverted.

A

If a spherical convex mirror has a radius of curvature R, the magnitude of its focal length is A) R/2. B) R/4. C) R. D) 2R. E) 4R.

A

Light enters air from water. The angle of refraction will be A) greater than the angle of incidence. B) equal to the angle of incidence. C) less than the angle of incidence.

A

Light goes from material having a refractive index of n1 into a material with refractive index n2. If the refracted light is bent away from the normal, what can you conclude about the indices of refraction? A) n1 > n2 B) n1 ≥ n2 C) n1 < n2 D) n1 ≤ n2 E) n1 = n2

A

Single convex spherical mirrors produce images that A) are always smaller than the actual object. B) are always larger than the actual object. C) are always the same size as the actual object. D) could be larger than, smaller than, or the same size as the actual object, depending on the placement of the object. E) are sometimes real.

A

The index of refraction of a type of glass is 1.50, and the index of refraction of water is 1.33. If light enters water from this glass, the angle of refraction will be A) greater than the angle of incidence. B) equal to the angle of incidence. C) less than the angle of incidence.

A

Which statements about images are correct? (There could be more than one correct choice.) A) A virtual image cannot be formed on a screen. B) A virtual image cannot be viewed by the unaided eye. C) A virtual image cannot be photographed. D) A real image must be erect. E) Mirrors always produce real images because they reflect light.

A

Starting from very far away, an object is moved closer and closer to a diverging lens, eventually reaching the lens. What happens to its image formed by that lens? (There could be more than one correct choice.) A) The image gets closer and closer to the lens. B) The image gets farther and farther from the lens. C) The image always remains virtual. D) The image eventually changes from real to virtual. E) The image keeps getting larger and larger.

A, C, E

Which of the following terms describe lenses that are thicker at the center than at the edges? (There could be more than one correct choice.) A) converging lenses B) diverging lenses C) concave lenses D) convex lenses

A, D

A convex lens has focal length f. If an object is placed at a distance beyond 2f from the lens on the principal axis, the image is located at a distance from the lens A) of 2f. B) between f and 2f. C) of f. D) between the lens and f. E) of infinity.

B

A convex mirror has a focal length of magnitude f. An object is placed in front of this mirror at a point f from the face 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.

B

An upright object is 50 cm from a concave mirror of radius 60 cm. The character of the image is A) real and upright B) real and inverted C) virtual and upright D) virtual and inverted

B

If a spherical concave mirror has a radius of curvature R, its focal length is A) R/4. B) R/2. C) R. D) 2R. E) 4R.

B

If an object is placed at the center of curvature of concave mirror, the image formed by the mirror is located A) out beyond the center of curvature. B) at the center of curvature. C) between the center of curvature and the focal point. D) at the focal point. E) at infinity.

B

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 in the water that is greater than 48.8° will be A) totally absorbed by the water. B) totally reflected. C) partially reflected and partially transmitted. D) totally transmitted.

B

The focal length of a concave mirror has a magnitude of 20 cm. What is its radius of curvature? A) 10 cm B) 40 cm C) -40 cm D) 20 cm E) -20 cm

B

The image formed by a single concave lens A) is always real. B) is always virtual. C) could be real or virtual, depending on whether the object distance is smaller or greater than the focal length. D) could be real or virtual, but is always real when the object is placed at the focal point. E) is always inverted.

B

Which of the following terms describe lenses that are thinner at the center than at the edges? (There could be more than one correct choice.) A) converging lenses B) diverging lenses C) concave lenses D) convex lenses

B, C

An object is placed in front of a thin lens. Which statements are correct in describing the image formed by the lens? (There could be more than one correct choice.) 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 lens is concave, the image must be virtual. E) If the lens is convex, the image must be real.

B, D

Which of following statements about the image formed by a single diverging lens are true? (There could be more than one correct choice.) A) The image is always real. B) The image is always virtual. C) The image is always inverted. D) The image is always upright. E) The image is always smaller than the object.

B, D

Which of the following statements about spherical mirrors is correct? (There could be more than one correct choice.) 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) A convex mirror always produces an upright image.

B, E

A beam of light that is parallel to the principal axis strikes 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.

C

A convex lens has focal length f. If an object is located at "infinity" (very far away), the image formed is located at a distance from the lens A) of 2f. B) between f and 2f. C) of f. D) between the lens and f. E) of infinity.

C

A lighted candle is placed a short distance from a plane mirror, as shown in the figure. At which location will the image of the flame appear to be located? A) at A B) at B C) at C D) at M (at the mirror)

C

If a single lens forms a virtual image of an object, then A) the lens must be a diverging lens. B) the lens must be a converging lens. C) the lens could be either a diverging or a converging lens. D) the image must be inverted. E) the object must be between the lens and its focal point.

C

If the index of refraction of a material is 2, this means that light travels A) 2 times as fast in air as it does in vacuum. B) 2 times as fast in the material as it does in air. C) 2 times as fast in vacuum as it does in the material. D) 2 times as fast in the material than it does in vacuum. E) 1/2 as fast in air as it does in the material.

C

If the magnification of a mirror or lens is negative, it means that A) the image is smaller than the object. B) the image is inverted and smaller than the object. C) the image is inverted. D) the object is farther from the mirror (or lens) than the image. E) the image is farther from the mirror (or lens) than the object.

C

If you stand in front of a convex mirror, at the same distance from it as its focal length, A) you won't see your image because there is none. B) you won't see your image because it is focused at infinity. C) you will see your image and you will appear smaller than you. D) you will see your image and you will appear larger than you. E) you will see your image and it will be the same size as you except upside down.

C

If you stand in front of a convex mirror, at the same distance from it as its radius of curvature, A) you won't see your image because there is none. B) you won't see your image because it is focused at infinity. C) you will see your image and you will appear smaller than you. D) you will see your image and you will appear larger than you. E) you will see your image and it will be the same size as you except upside down.

C

Is it possible to see a virtual image? A) No, since the rays that seem to emanate from a virtual image do not in fact emanate from the image. B) No, since virtual images do not really exist. C) Yes because the rays that appear to come from a virtual image can be focused by the eye just like those from an object. D) Yes, but only by using an additional lens to form a real image before the light reaches the eye.

C

Light enters glass from air. The angle of refraction will be A) greater than the angle of incidence. B) equal to the angle of incidence. C) less than the angle of incidence.

C

Sometimes when you look into a curved mirror you see a magnified image (a great big you) and sometimes you see a diminished image (a little you). If you look at the bottom (convex) side of a shiny spoon, what will you see? A) You won't see an image of yourself because no image will be formed. B) You will see a little you, upside down. C) You will see a little you, right side up. D) You will see a little you, but whether you are right side up or upside down depends on how near you are to the spoon. E) You will either see a little you or a great big you, depending on how near you are to the spoon.

C

The focal length of a convex mirror is has a magnitude of 20 cm. What is its radius of curvature? A) -10 cm B) 40 cm C) -40 cm D) -20 cm E) 20 cm

C

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) a real image behind 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.

C

Which one 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) virtual and larger than the object

C

An object is placed on the left side of a thin lens, and the image of this object is formed on the left side of the lens. Which of the following statements must be true? (There could be more than one correct choice.) A) The lens must be a diverging lens, and the image is upright. B) The lens must be a converging lens, and the image is upright. C) The image is upright and virtual. D) The lens could be either a converging or a diverging lens, and the image is upright. E) The image is inverted and real.

C, D

A beam of light that is parallel to the principal axis strikes 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.

D

A convex lens has focal length f. If an object is placed at a distance between f and 2f from the lens on the principal axis, the image is located at a distance from the lens A) of 2f. B) between f and 2f. C) of f. D) that is greater than 2f. E) of infinity.

D

A light beam has speed c in vacuum and speed v in a certain plastic. The index of refraction n of this plastic is A) n = cv. B) n = (v/c)2. C) n = v/c. D) n = c/v. E) n = (c/v)2.

D

A negative magnification for a mirror means that A) the image is inverted, and the mirror could be either concave or convex. B) the image is upright, and the mirror is convex. C) the image is inverted, and the mirror is convex. D) the image is inverted, and the mirror is concave. E) the image is upright, and the mirror could be either concave or convex.

D

An object is placed in front of a convex mirror at a distance larger than twice the magnitude of 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.

D

Single concave spherical mirrors produce images that A) are always smaller than the actual object. B) are always larger than the actual object. C) are always the same size as the actual object. D) could be smaller than, larger than, or the same size as the actual object, depending on the placement of the object. E) are always real.

D

Starting from very far away, an object is moved closer and closer to a converging lens, eventually reaching the lens. What happens to its image formed by that lens? (There could be more than one correct choice.) A) The image gets closer and closer to the lens. B) The image gets farther and farther from the lens. C) The image eventually changes from virtual to real. D) The image eventually changes from real to virtual. E) The image keeps getting larger and larger.

D

Suppose you place an object in front of a concave mirror. Which of the following statements must be true? (There could be more than one correct choice.) A) The image of the object will always be smaller than the object. B) No matter where you place the object, a real image of the object will be formed. C) The image of the object will always be inverted. D) If you position the object between the mirror and the focal point of the mirror, its image must be upright and virtual. E) No matter where you place the object, the image of the object will always be virtual and upright.

D

Suppose you wanted to start a fire using a mirror to focus sunlight. Which of the following statements is most accurate? A) It would be best to use a plane mirror. B) It would be best to use a convex mirror. C) It would be best to use a concave mirror, with the object to be ignited positioned at the center of curvature of the mirror. D) It would be best to use a concave mirror, with the object to be ignited positioned halfway between the mirror and its center of curvature. E) One cannot start a fire using a mirror, since mirrors form only virtual images.

D

Which one of the following numbers is the correct magnification produced by a plane mirror? A) 1/2 B) 1/4 C) 2 D) 1 E) 3/2

D

Which statement about a single thin lens is correct? A) A converging lens always produces a real inverted image. B) A diverging lens always produces a virtual inverted image. C) A converging lens sometimes produces a real upright image. D) A diverging lens always produces a virtual upright image. E) A diverging lens produces a virtual upright image only if the object is located between the lens and its focal point.

D

A beam of light traveling in air strikes a glass slab at an angle of incidence less than 90°. After entering the glass slab, what does the beam of light do? (There could be more than one correct choice.) A) I follows the same path as before it struck the glass. B) It follows the normal to the glass slab. C) It bends away from the normal at the point of contact. D) It bends closer to the normal at the point of contact. E) It slows down.

D, E

An object is placed to the left of a spherical mirror in front of the mirror. If the image of the object is formed on the right side of the mirror, which of the following statements must be true? (There could be more than one correct choice.) A) The image is upright and the mirror must be convex. B) The image is inverted and real, and the mirror must be convex. C) The image is upright and the mirror must be concave. D) The image is upright and virtual. E) The mirror could be either concave or convex.

D, E

As you walk away from a plane mirror on a wall, the height of your image A) gets smaller. B) may or may not get smaller, depending on where the observer is positioned. C) is always a real image, no matter how far you are from the mirror. D) changes from being a virtual image to a real image as you pass the focal point. E) is always the same size.

E

Which of following statements about the image formed by a single converging lens are true? (There could be more than one correct choice.) A) The image is always real. B) The image is always virtual. C) The image is always inverted. D) The image is always upright. E) None of the above choices are correct.

E

You may have seen ambulances on the street with the letters of the word AMBULANCE written on the front of them, in such a way as to appear correctly when viewed in your car's rear-view mirror. (See the figure.) How do the letters appear when you look directly at the ambulance (not through the mirror)? A) a B) b C) c D) d E) e

E