PHY 112 Exam 3 (Final Review) (LAST 3 CHAP. HW)

An object is placed near two perpendicular plane mirrors as shown in the figure. How many images will be formed? 2 5 1 3 4

3

The drawing shows a top view of an object to the right of a plane mirror. An observer looks into the mirror. At what location, A, B, C, or D, does the observer see the image? A The observer does not see an image because the observer is closer to the mirror than is the object. D C B

A

The radial lines pointing outward away from the wave source and perpendicular to the wave fronts are called? A. Light lines B. Rays C. Arrows D. Light vectors

B. Rays

The drawing shows a top view of an object located to the right of a mirror. A single ray of light is shown leaving the object. After reflection from the mirror, through which location, A, B, C, or D, does the ray pass? C D B A

C

Which of the following is true at a very far distance from a wave source? A. The wave fronts reaching you are curved, and the rays are parallel to each other. B. The wave fronts reaching you form flat planes, and the rays are not parallel to each other. C. The wave fronts reaching you are curved, and the rays are not parallel to each other. D. The wave fronts reaching you form flat planes, and the rays are parallel to each other.

D. The wave fronts reaching you form flat planes, and the rays are parallel to each other.

True or False: It is possible to use a convex spherical mirror to produce an enlarged image. True False

False

True or False: Compact discs (CDs) and digital video discs (DVDs) rely on interference effects of light for their operation. False True

True

True or False: X-ray diffraction from crystalline matter can provide information on the spacing of atoms and the nature of the crystal structure. True False

True

(a) When you look at the backside of a shiny teaspoon held at arm's length, do you see yourself upright or upside down? (b) When you look at the other side of the spoon, do you see yourself upright or upside down? Assume in both cases that the distance between you and the spoon is greater than the focal length of the spoon. a. (a) upright (b) upside down b. (a) upright (b) upright c. (a) upside down (b) upside down d. (a) upside down (b) upright

a. (a) upright (b) upside down

A section of the surface of a hollow sphere has a radius of curvature of 0.60 m, and both the inside and outside surfaces have a mirror-like finish. What are the focal lengths of the inside and outside surfaces? a. +0.3 m and -0.3 m b. -0.6 m and +0.6 m c. -0.3 m and +0.3 m d. +0.6 m and -0.6 m

a. +0.3 m and -0.3 m

If the speed of light in some unknown material is 2.00 × 108 m/s, what is the index of refraction of the medium? a. 1.50 b. 2.00 c. 0.67 d. 1.88

a. 1.50

Light from a laser pointer goes through a window composed of crown glass, which has an index of refraction of n= 1.523. What is the speed of the light while it is in the window glass? a. 1.97 × 10^8 m/s b. 4.57 × 10^8 m/s c. 3.00 × 10^8 m/s d. 1.52 × 10^8 m/s

a. 1.97 × 10^8 m/s

Two waves have amplitudes of 10 m and 7 m, respectively. What are the maximum and minimum amplitudes of the resultant wave if they interfere first constructively, and then destructively? a. 17 m and 3 m b. 70 m and 1.4 m c. 17 m and 0 m d. 10 m and 3 m

a. 17 m and 3 m

The thickness (t) of the pits in a CD track is chosen to be equal to which of the following? a. 2t=λcoating/2 b. 2t=λcoating/4 c. t=λcoating d. 2t=λcoating

a. 2t=λcoating/2

A friend is standing 2 m in front of a plane mirror. You are standing 3 m directly behind your friend. What is the distance between you and the image of your friend? a. 7 m b. 3 m c. 5 m d. 10 m e. 2 m

a. 7 m

Incident light moves through liquid water (n= 1.33) and passes through an interface between water and glass (n= 1.52) at some angle other than the normal to the interface. Which of the following is true of the refracted beam? a. It bends towards the normal to the interface. b. It bends away from the normal to the interface. c. It does not deviate from the incident path.

a. It bends towards the normal to the interface.

In order to correct for spherical aberration in a converging lens, you use a circular hole that has a diameter that is half that of the lens to block rays far way from the principal axis. You expect the image of a far away object to be: a. Sharper but dimmer. b. Sharper, but with half the image blocked. c. Sharper, but with the image in a different location. d. Sharper, but smaller.

a. Sharper but dimmer.

A section of the surface of a hollow sphere has a radius of curvature of 0.60 m, and both the inside and outside surfaces have a mirror-like polish. What are the focal lengths of the inside and outside surfaces? a. The focal length of the inside is +0.30 m and the focal length of the outside is -0.30 m. b. The focal length of the inside is -0.30 m and the focal length of the outside is +0.30 m. c. The focal length of the inside is -0.30 m and the focal length of the outside is -0.30 m. d. The focal length of the inside is +0.30 m and the focal length of the outside is +0.30 m.

a. The focal length of the inside is +0.30 m and the focal length of the outside is -0.30 m.

What is true of the image formed by a diverging lens when the object is placed far away? a. The image is much smaller than the object, virtual, and located near the focus on the same side of the lens as the object. b. The image is much smaller than the object, real, and located near the focus on the same side of the lens as the object. c. The image is much smaller than the object, real, and located near the focus on the opposites side of the lens as the object. d. The image is much smaller than the object, virtual, and located near the focus on the opposites side of the lens as the object.

a. The image is much smaller than the object, virtual, and located near the focus on the same side of the lens as the object.

A sound wave has a much greater wavelength than a light wave. If both waves pass through an open doorway, which one, if either, will diffract to a greater extent. a. The sound wave b. The light wave c. Both would diffract by the same amount.

a. The sound wave

A diffraction pattern is created on a screen when blue light is passed through a single slit. Does the central bright maximum in this pattern become wider or narrower, when the blue light is replaced by red light? a. Wider b. The width remains the same. c. Narrower

a. Wider

For specular reflection from a smooth surface, the angle of incidence measured relative to the normal to the surface ... a. will be equal to the angle of reflection as measured relative to the normal to the surface. b. must always be equal to 90o. c. must always be equal to zero. d. will be unequal to the angle of reflection as measured relative to the normal to the surface.

a. will be equal to the angle of reflection as measured relative to the normal to the surface.

Where is the image located in the case of an object placed at a distance do=2f to the left of a converging lens? a. -2f b. 2f c. f/2 d. f

b. 2f

Where is the image located in the case of an object placed at a distance do=2f to the left of a converging lens? a.-2f b. 2f c. f/2 d. f

b. 2f

An incident beam of light moves through liquid water (n= 1.33) and impinges upon an interface with glass (n= 1.52) with an angle of incidence of 47.0o.What is the angle of the refracted beam (i.e., in the glass) with respect to the surface normal? a. 47.0o b. 39.8o c. 28.6o d. 56.7o

b. 39.8o

Based on how the size of your pupils responds to light levels, when would human eyes have their best optical resolution? a. In bright sunshine. b. At night c. Light levels would not affect optical resolution

b. At night

Light reflecting off of a rough piece of paper is an example of? a. Specular reflection b. Diffuse reflection c. Reverse reflection d. Secondary reflection

b. Diffuse reflection

If a person with normal vision looks through a diverging lens, does this make their vision farsighted or nearsighted, and why? a. Nearsighted: the image forms in front of the retina. b. Farsighted: the image forms behind the retina. c. Nearsighted: the image forms behind the retina. d. Farsighted: the image forms in front of the retina.

b. Farsighted: the image forms behind the retina.

Is it possible for a converging lens to focus the image of an object on a screen if the object located between the focal point and the lens? a. Yes. b. No, because the image is virtual and forms on the same side of the lens as the object. c. No, because there is no focused image of any kind formed in this case.

b. No, because the image is virtual and forms on the same side of the lens as the object.

Because of spherical aberration, a parallel ray far from the principal axis does not pass through the focal point upon reflection (see figure). How could you change the shape of the mirror, so the ray does pass through F after reflection? a. Close the mirror down by bringing the ends of the mirror closer to the principal axis. b. Open it up by moving the ends of the mirror away from the principal axis, thereby creating a more gentle curvature.

b. Open it up by moving the ends of the mirror away from the principal axis, thereby creating a more gentle curvature.

What is true of the image formed by a diverging lens when the object is placed far away? a. The image is much smaller than the object, real, and located near the focus on the opposites side of the lens as the object. b. The image is much smaller than the object, virtual, and located near the focus on the same side of the lens as the object. c. The image is much smaller than the object, virtual, and located near the focus on the opposites side of the lens as the object. d. The image is much smaller than the object, real, and located near the focus on the same side of the lens as the object.

b. The image is much smaller than the object, virtual, and located near the focus on the same side of the lens as the object.

Which of the following is not a property of an image formed by a plane mirror? a. The image is located as far behind the mirror as the object is in front. b. The image is real. c. The image is reversed from left to right. d. The image is upright with respect to the object. e. The image is virtual.

b. The image is real.

Which one of the following statements is not a characteristic of a plane mirror? a. The image is always upright. b. The image is real. c. The magnification is +1. d. The image and object distances are equal in magnitude. e. The image is reversed right to left.

b. The image is real.

Suppose the light waves coming from both slits in a Young's double-slit experiment had their phases shifted by an amount equivalent to a half-wavelength. Would the pattern on the screen be the same, or would the bright and dark fringes be interchanged? a. The bright and dark fringes would be interchanged. b. The pattern on the screen would be the same.

b. The pattern on the screen would be the same.

You are using a small telescope to view two closely spaced light bulbs located a mile away. Each light bulb is emitting blue light. At this distance, the light bulbs are still too close together for you to distinguish them as separate bulbs. If they were emitting red light instead, would you have a better or worse chance of distinguishing them as separate bulbs? a. Better b. Worse c. The color of light would make no difference.

b. Worse

Two sources of waves are in phase and produce identical waves. These sources are mounted at the corners of a square and broadcast waves uniformly in all directions. At the center of the square, will the waves always produce constructive interference no matter which two corners of the square are occupied by the sources? a. No b. Yes

b. Yes

If a clock is held in front of a mirror, its image is reversed left to right. From the point of view of a person looking into the mirror, does the image of the second hand rotate in the reversed (counterclockwise) direction? a. No. b. Yes.

b. Yes.

Calculate the magnification of the image when an object is placed at a distance do=2f to the left of a converging lens. Is the image inverted or upright? a. m= -2, inverted. b. m= -1, inverted. c. m= -1, upright. d. m= 1, upright. e. m= 2, upright.

b. m= -1, inverted.

A ray is __________ a. always parallel to other rays. b. parallel to the velocity of the wave. c. perpendicular to the velocity of the wave. d. parallel to the wave fronts.

b. parallel to the velocity of the wave.

The two loudspeakers in the drawing are producing identical sound waves. The waves spread out and overlap at the point P. This situation is analogous to Young's double-slit experiment, except that sound waves are being used. What is the difference ℓ2−ℓ1 in the two path lengths if point P is at the third sound intensity minimum from the central sound intensity maximum? Express this difference in terms of the wavelength λ of the sound. a. 3/2λ b. 3λ c. 5/2λ d. 1/2λ e. λ

c. 5/2λ

The figure shows a light ray undergoing multiple reflections from a mirrored corridor. The walls of the corridor are either parallel or perpendicular to one another. If the initial angle of incidence is 35o, what is the angle of reflection (θ) when the ray makes its last reflection? a. 35o b. 45o c. 55o d. 65o

c. 55o

In light sources that utilize electrical gas discharge, like in neon signs, the emitted light is composed of discrete colors rather than the full spectrum (such as in sunlight). Even though the gas discharge source emits multiple colors of light, your eyes can only detect one color. If the light from a gas discharge source is passed through a prism, what will you see? a. A continuous spectrum, the same as for sunlight. b. Only one color: the one that your eyes detect emitted from the source. c. A series of individual colors located where they would otherwise be in the full spectrum (but the other colors in the spectrum are missing).

c. A series of individual colors located where they would otherwise be in the full spectrum (but the other colors in the spectrum are missing).

How does the critical angle (θc) for total internal reflection change when ratio between indices of refraction n2/n1 of the two media decreases? a. It does not change. b. It gets larger (relative to the normal) c. It gets smaller (relative to the normal)

c. It gets smaller (relative to the normal)

Consider a converging lens with a focal point F. Without changing the shape and size of the lens, what could you do to move the focus closer to the lens? a. Make the lens from a material with a smaller index of refraction. b. There is nothing you can do: the shape alone determines the focal length. c. Make the lens from a material with a larger index of refraction.

c. Make the lens from a material with a larger index of refraction.

Is it possible for a converging lens to focus the image of an object on a screen if the object located between the focal point and the lens? a. No, because there is no focused image of any kind formed in this case. b. Yes. c. No, because the image is virtual and forms on the same side of the lens as the object.

c. No, because the image is virtual and forms on the same side of the lens as the object.

Should you expect chromatic aberration in the real images formed by a concave mirror? a. Yes, the angle of reflection depends on the wavelength (color) of the light. b. Yes, they have spherical symmetry just like spherical lenses. c. No, chromatic aberration is a result of dispersion caused by differing indices of refraction for different colors, something that does not occur in mirrors.

c. No, chromatic aberration is a result of dispersion caused by differing indices of refraction for different colors, something that does not occur in mirrors.

If a glass prism (n= 1.52) were surrounded by water (n= 1.33) rather than air (n= 1.00) how would the dispersion of the light change? a. The colors would be more spread out (i.e., more dispersed). b. There would be no change. c. The colors would be less spread out (i.e., less dispersed).

c. The colors would be less spread out (i.e., less dispersed).

X-rays diffract from crystalline matter because... a. The wavelength of the X-rays is much shorter than the atomic spacing in matter. b. The wavelength of the X-rays is much larger than the atomic spacing in matter. c. The wavelength of the X-rays is comparable to the atomic spacing in matter.

c. The wavelength of the X-rays is comparable to the atomic spacing in matter.

A wave front __________ a. is parallel to a ray. b. is a surface that contains one cycle of the wave. c. is a surface on which all points of the wave are in the same phase of motion. d. is always a spherical surface. e. is always a plane surface.

c. is a surface on which all points of the wave are in the same phase of motion.

Calculate the magnification of the image when an object is placed at a distance do=2f to the left of a converging lens. Is the image inverted or upright? a. m= 1, upright. b. m= 2, upright. c. m= -1, inverted. d. m= -2, inverted. e. m= -1, upright.

c. m= -1, inverted.

When diffuse reflection from a surface occurs, __________ a. the reflected rays are parallel to each other. b. an individual ray of light does not obey the law of reflection. c. the reflected rays are not parallel to each other. d. there are no reflected rays.

c. the reflected rays are not parallel to each other.

The photograph shows an experimental device at Sandia National Laboratories in New Mexico. This device is a mirror that focuses sunlight to heat sodium to a boil, which then heats helium gas in an engine. The engine does the work of driving a generator to produce electricity. The sodium unit and the engine are labeled in the photo. (a) What kind of mirror, concave or convex, is being used? (b) Where is the sodium unit located relative to the mirror? Express your answer in terms of the focal length of the mirror. a. (a) concave (b) a distance -f from the mirror b. (a) convex (b) a distance -f from the mirror c. (a) convex (b) a distance +f from the mirror d. (a) concave (b) a distance +f from the mirror

d. (a) concave (b) a distance +f from the mirror

An incident beam of light travels through glass (n= 1.52) and impinges upon an interface with liquid water (n= 1.33). What is the critical angle (θc) for total internal reflection at the interface (i.e., with respect to the surface normal)? a. 0o b. 45.0o c. 29.0o d. 61.0o

d. 61.0o

Which statement regarding real and virtual images is correct? a. A virtual image is always smaller than the object, whereas a real image is always larger. b. Rays of light emanate from a virtual image, but only appear to do so from a real image. c. A virtual image is always inverted relative to the object, whereas a real image is never inverted. d. Rays of light emanate from a real image, but only appear to do so from a virtual image. e. A virtual image is always larger than the object, whereas a real image is always smaller.

d. Rays of light emanate from a real image, but only appear to do so from a virtual image.

A person needs corrective glasses with a refractive power of -2.0 diopters. What is the focal length of the lens, and is the person nearsighted or farsighted? a. f= -0.5 m; farsighted b. f= -2 m; nearsighted c. f= -2 m; farsighted d. f= -0.5 m; nearsighted

d. f= -0.5 m; nearsighted

Light rays that are near and parallel to the principal axis of a concave mirror converge to a point 18 cm in front of the mirror. What is the radius of curvature of the mirror? a. 18 cm b. 9 cm c. -18 cm d. -9 cm e. 36 cm

e. 36 cm

Which one of the following statements concerning rays is false? a. Rays for a plane wave are parallel to each other. b. Rays point outward from the wave source. c. Rays point in the direction of the wave velocity. d. Rays are radial lines that originate from a point source of waves. e. Rays are parallel to the wave front.

e. Rays are parallel to the wave front.

Which one of the following phrases most accurately describes the term wave front? a. the surface of a plane mirror b. the surface of a convex mirror c. a surface upon which a wave is incident d. a surface that is parallel to the direction of wave propagation e. a surface of constant phase within a wave

e. a surface of constant phase within a wave

Rays of light coming from the sun (a very distant object) are near and parallel to the principal axis of a concave mirror. After reflecting from the mirror, where will the rays cross each other at a single point? The rays __________ a. will cross at the point where the principal axis intersects the mirror. b. will cross at the center of curvature. c. will not cross each other after reflecting from a concave mirror. d. will cross at a point beyond the center of curvature. e. will cross at the focal point.

e. will cross at the focal point.

Suppose you are standing in front of a concave spherical mirror. Which of the following image properties are possible? a. Your image is upright. b. Your image is inverted. c. Your image is enlarged. d. Your image is reduced. e. Your image is real. f. Your image is virtual. g. All of the above.

g. All of the above.