A biologist keeps a specimen of his favorite beetle

Problem 1CQ The idea of light rays goes back, to the ancient Greeks. However, they believed that “visual rays” were emitted by eyes. If you were transported back in time, what arguments would you present to those early scientists to convince them that vision has something to do with rays going into, rather than out of, eyes?

Problem 1P A 5.0-ft-tall girl stands on level ground. The sun is 25° above the horizon. How long is her shadow?

Problem 2CQ Is there any property that distinguishes a light ray emitted by a light bulb and one that has been diffusely reflected by the page of a book? Explain.

Problem 2P A 10-cm-diameter disk emits light uniformly from its surface. 20 cm from this disk, along its axis, is an 8.0-cm-diameter opaque black disk; the faces of the two disks are parallel. 20 cm beyond the black disk is a white viewing screen. The lighted disk illuminates the screen, but there’s a shadow in the center due to the black disk. What is the diameter of the completely dark part of this shadow?

Problem 3CQ If you turn on your car headlights during the day, the road ahead of you doesn’t appear to get brighter. Why not?

Problem 3P A point source of light illuminates an aperture 2.00 m away. A 12.0-cm-wide bright patch of light appears on a screen 1.00 m behind the aperture. How wide is the aperture?

Problem 4CQ Can you see the rays from the sun on a clear day? Why or why not? How about when they stream through a forest on a foggy morning? Why or why not?

Problem 4P The mirror in Figure P18.4 deflects a horizontal laser beam by 60°. What is the angle ??

Problem 5CQ If you take a walk on a summer night along a dark, unpaved road in the woods, with a flashlight pointing at the ground several yards ahead to guide your steps, any water-filled potholes are noticeable because they appear much darker than the surrounding dry road. Explain why.

Problem 5P Figure P18.5 shows an object O in front of a plane mirror. Use ray tracing to determine from which locations A–D the object’s image is visible.

Problem 6P A light ray leaves point A in Figure P18.6, reflects from the mirror, and reaches point B. How far below the top edge does the ray strike the mirror?

Problem 6CQ You are looking at the image of a pencil in a mirror, as shown in Figure Q18.5 . a. What happens to the image you see if the top half of the mirror, down to the midpoint, is covered with a piece of cardboard? Explain. b. What happens to the image you see if the bottom half of the mirror is covered with a piece of cardboard?

Problem 7CQ In The Toilet of Venus by Velázquez (see Figure Q18.6 ), we can see the face of Venus in the mirror. Can she see her own face in the mirror, when the mirror is held as shown in the picture? If yes, explain why; if not, what does she see instead?

Problem 7P It is 165 cm from your eyes to your toes. You’re standing 200 cm in front of a tall mirror. How far is it from your eyes to the image of your toes?

Problem 8P A ray of light impinges on a mirror as shown in Figure P18.8. A second mirror is fastened at 90° to the first. a. After striking both mirrors, at what angle relative to the incoming ray does the outgoing ray emerge? b. What is the answer if the incoming angle is 30°?

Problem 8CQ In Manet’s A Bar at the Folies-Bergère (see Figure Q18.7 ) the reflection of the barmaid is visible in the mirror behind her. Is this the reflection you would expect if the mirror’s surface is parallel to the bar? Where is the man seen facing her in the mirror actually standing?

Problem 9CQ Explain why ambulances have the word “AMBULANCE” written backward on the front of them.

Problem 9P Ared ball is placed at point A in Figure 9. a. How many images are seen by an observer at point O? b. Where is each image located? c. Draw a ray diagram showing the formation of each image.

Problem 10CQ a. Consider one point on an object near a lens. What is the minimum number of rays needed to locate its image point? b. For each point on the object, how many rays from this point actually strike the lens and refract to the image point?

Problem 10P An underwater diver sees the sun 50° above horizontal. How high is the sun above the horizon to a fisherman in a boat above the diver?

Problem 11CQ When you look at your reflection in the bowl of a spoon, it is upside down. Why is this?

Problem 11P A laser beam in air is incident on a liquid at an angle of 37° with respect to the normal. The laser beam’s angle in the liquid is 26°. What is the liquid’s index of refraction?

Problem 12CQ A concave mirror brings the sun’s rays to a focus at a distance of 30 cm from the mirror. If the mirror were submerged in a swimming pool, would the sun’s rays be focused nearer to, farther from, or at the same distance from the mirror?

Problem 12P A 1.0-cm-thick layer of water stands on a horizontal slab of glass. A light ray in the air is incident on the water 60° from the normal. After entering the glass, what is the ray’s angle from the normal?

Problem 13P A 4.0-m-wide swimming pool is filled to the top. The bottom of the pool becomes completely shaded in the afternoon when the sun is 20° above the horizon. How deep is the pool?

Problem 13CQ A student draws the ray diagram shown in Figure Q18.12 but forgets to label the object, the image, or the type of lens used. Using the diagram, explain whether the lens is converging or diverging, which arrow represents the object, and which represents the image.

Problem 14CQ An object at distance s from a concave mirror of focal length f produces a real image at distance s?from the mirror. Suppose the mirror is replaced by a new mirror, at the same location, with focal length .Will the new image be real or virtual? Will its distance from the mirror be more or less than s??Explain.

Problem 14P A diamond is underwater. A light ray enters one face of the diamond, then travels at an angle of 30° with respect to the normal. What was the ray’s angle of incidence on the diamond?

Problem 15P A thin glass rod is submerged in oil. What is the critical angle for light traveling inside the rod?

Problem 15CQ A lens can be used to start a fire by focusing an image of the sun onto a piece of flammable material. All other things being equal, would a lens with a short focal length or a long focal length be better as a fire starter? Explain.

Problem 16MCQ Question are concerned with the situation sketched in Figure Q18.17 , in which a beam of light in the air encounters a transparent block with index of refraction n = 1.53. Some of the light is reflected and some is refracted. What is ? A. 40° B. 45° C. 50° D. 90°

Problem 16P A biologist keeps a specimen of his favorite beetle embedded in a cube of polystyrene plastic. The hapless bug appears to be 2.0 cm within the plastic. What is the beetle’s actual distance beneath the surface?

Problem 17MCQ Question are concerned with the situation sketched in Figure Q18.17 , in which a beam of light in the air encounters a transparent block with index of refraction n = 1.53. Some of the light is reflected and some is refracted. What is ? A. 20° B. 30° C. 50° D. 60°

Problem 17P A fish in a flat-sided aquarium sees a can of fish food on the counter. To the fish’s eye, the can looks to be 30 cm outside the aquarium. What is the actual distance between the can and the aquarium? (You can ignore the thin glass wall of the aquarium.)

Problem 18MCQ Question are concerned with the situation sketched in Figure Q18.17 , in which a beam of light in the air encounters a transparent block with index of refraction n = 1.53. Some of the light is reflected and some is refracted. Is there an angle of incidence between 0° and 90° such that all of the light will be reflected? A. Yes, at an angle greater than 50° B. Yes, at an angle less than 50° C. No

Problem 18P A swim mask has a pocket of air between your eyes and the flat glass front. a. If you look at a fish while swimming underwater with a swim mask on, does the fish appear closer or farther than it really is? Draw a ray diagram to explain. b. Does the fish see your face closer or farther than it really is? Draw a ray diagram to explain.

Problem 19P An object is 30 cm in front of a converging lens with a focal length of 10 cm. Use ray tracing to determine the location of the image. Is the image upright or inverted? Is it real or virtual?

Problem 19MCQ A 2.0-m-tall man is 5.0 m from the converging lens of a camera. His image appears on a detector that is 50 mm behind the lens. How tall is his image on the detector? A. 10 mm B. 20 mm C. 25 mm D. 50 mm

Problem 20MCQ You are 2.4 m from a plane mirror, and you would like to take a picture of yourself in the mirror. You need to manually adjust the focus of the camera by dialing in the distance to what you are photographing. What distance do you dial in? A. 1.2 m B. 2.4 m C. 3.6 m D. 4.8 m

Problem 20P An object is 6.0 cm in front of a converging lens with a focal length of 10 cm. Use ray tracing to determine the location of the image. Is the image upright or inverted? Is it real or virtual?

Problem 21MCQ Figure 21 shows an object and lens positioned to form a well-focused, inverted image on a viewing screen. Then a piece of cardboard is lowered just in front of the lens to cover the top half of the lens. What happens to the image on the screen? Figure 21 A. Nothing. B. The upper half of the image will vanish. C. The lower half of the image will vanish. D. The image will become fuzzy and out of focus. E. The image will become dimmer.

Problem 21P An object is 20 cm in front of a diverging lens with a focal length of 10 cm. Use ray tracing to determine the location of the image. Is the image upright or inverted? Is it real or virtual?

Problem 22MCQ A real image of an object can be formed by A. A converging lens. B. A plane mirror. C. A convex mirror. D. Any of the above.

Problem 22P An object is 15 cm in front of a diverging lens with a focal length of 10 cm. Use ray tracing to determine the location of the image. Is the image upright or inverted? Is it real or virtual?

Problem 23MCQ An object is 40 cm from a converging lens with a focal length of 30 cm. A real image is formed on the other side of the lens, 120 cm from the lens. What is the magnification? A. 2.0 B. 3.0 C. 4.0 D. 1.33 E. 0.33

Problem 23P A concave cosmetic mirror has a focal length of 40 cm. A 5-cm-long mascara brush is held upright 20 cm from the mirror. Use ray tracing to determine the location and height of its image. Is the image upright or inverted? Is it real or virtual?

Problem 24MCQ The lens in Figure Q18.25 is used to produce a real image of a candle flame. What is the focal length of the lens? A. 9.0 cm B. 12 cm C. 24 cm D. 36 cm E. 48 cm

Problem 24P A light bulb is 60 cm from a concave mirror with a focal length of 20 cm. Use ray tracing to determine the location of its image. Is the image upright or inverted? Is it real or virtual?

Problem 25MCQ A converging lens of focal length 20 cm is used to form a real image 1.0 m away from the lens. How far from the lens is the object? A. 20 cm B. 25 cm C. 50 cm D. 100 cm

Problem 26MCQ You look at yourself in a convex mirror. Your image is A. Upright. B. Inverted. C. It’s impossible to tell without knowing how far you are from the mirror and its focal length.

Problem 25P The illumination lights in an operating room use a concave mirror to focus an image of a bright lamp onto the surgical site. One such light has a mirror with a focal length of 15.0 cm. Use ray tracing to find the position of its lamp when the patient is positioned 1.0 m from the mirror (you’ll need a careful drawing to get a good answer).

Problem 26P A dentist uses a curved mirror to view the back side of teeth on the upper jaw. Suppose she wants an erect image with a magnification of 2.0 when the mirror is 1.2 cm from a tooth. (Treat this problem as though the object and image lie along a straight line.) Use ray tracing to decide whether a concave or convex mirror is needed, and to estimate its focal length.

Problem 27MCQ An object is 50 cm from a diverging lens with a focal length of -20 cm. How far from the lens is the image, and on which side of the lens is it? A. 14 cm, on the same side as the object B. 14 cm, on the opposite side from the object C. 30 cm, on the same side as the object D. 33 cm, on the same side as the object E. 33 cm, on the opposite side from the object

Problem 27P A convex mirror, like the passenger-side rearview mirror on a car, has a focal length of 2.0 m. An object is 4.0 m from the mirror. Use ray tracing to determine the location of its image. Is the image upright or inverted? Is it real or virtual?

Problem 28P An object is 6 cm in front of a convex mirror with a focal length of 10 cm. Use ray tracing to determine the location of the image. Is the image upright or inverted? Is it real or virtual?

Problem 29P For Problem calculate the image position and height. A 2.0-cm-tall object is 40 cm in front of a converging lens that has a 20 cm focal length. Step-by-step solution Step 1 of 3 Step 2 of 3

Problem 30P For Problem calculate the image position and height. A 1.0-cm-tall object is 10 cm in front of a converging lens that has a 30 cm focal length.

Problem 31P For Problem calculate the image position and height. A 2.0-cm-tall object is 15 cm in front of a converging lens that has a 20 cm focal length.

Problem 32P For Problem calculate the image position and height. A 1.0-cm-tall object is 75 cm in front of a converging lens that has a 30 cm focal length.

Problem 33P For Problem calculate the image position and height. A 2.0-cm-tall object is 15 cm in front of a diverging lens that has a -20 cm focal length.

Problem 34P For Problem calculate the image position and height. A 1.0-cm-tall object is 60 cm in front of a diverging lens that has a -30 cm focal length.

Problem 35P For Problem calculate the image position and height. A 3.0-cm-tall object is 15 cm in front of a convex mirror that has a -25 cm focal length.

Problem 36P For Problem calculate the image position and height. A 3.0-cm-tall object is 45 cm in front of a convex mirror that has a -25 cm focal length.

Problem 37P For Problem calculate the image position and height. A 3.0-cm-tall object is 15 cm in front of a concave mirror that has a 25 cm focal length.

Problem 38P For Problem calculate the image position and height. A 3.0-cm-tall object is 45 cm in front of a concave mirror that has a 25 cm focal length.

Problem 39P Starting 3.5 m from a department store mirror, Suzanne walks toward the mirror at 1.5 m/s for 2.0 s. How far is Suzanne from her image in the mirror after 2.0 s?

Problem 40GP You slowly back away from a plane mirror at a speed of 0.10 m/s. With what speed does your image appear to be moving away from you?

Problem 41GP At what angle ? should the laser beam in Figure P18.43 be aimed at the mirrored ceiling in order to hit the midpoint of the far wall?

Problem 42GP You’re helping with an experiment in which a vertical cylinder will rotate about its axis by a very small angle. You need to devise a way to measure this angle. You decide to use what is called an optical lever.You begin by mounting a small mirror on top of the cylinder. A laser 5.0 m away shoots a laser beam at the mirror. Before the experiment starts, the mirror is adjusted to reflect the laser beam directly back to the laser. Later, you measure that the reflected laser beam, when it returns to the laser, has been deflected sideways by 2.0 mm. How many degrees has the cylinder rotated? FIGURE 41

Problem 43GP Figure P18.45 shows a light ray incident on a polished metal cylinder. At what angle ? will the ray be reflected?

Problem 44GP The place you get your haircut has two nearly parallel mirrors 5.0 m apart. As you sit in the chair, your head is 2.0 m from the nearer mirror. Looking toward this mirror, you first see your face and then, farther away, the back of your head. (The mirrors need to be slightly nonparallel for you to be able to see the back of your head, but you can treat them as parallel in this problem.) How far away does the back of your head appear to be? Neglect the thickness of your head.

Problem 45GP You shine your laser pointer through the flat glass side of a rectangular aquarium at an angle of incidence of 45°. The index of refraction of this type of glass is 1.55. a. At what angle from the normal does the beam from the laser pointer enter the water inside the aquarium? b. Does your answer to part a depend on the index of refraction of the glass?

Problem 47GP What is the angle of incidence in air of a light ray whose angle of refraction in glass is half the angle of incidence?

Problem 46GP A ray of light traveling through air encounters a 1.2-cm-thick sheet of glass at a 35° angle of incidence. How far does the light ray travel in the glass before emerging on the far side?

Problem 48GP Figure P18.50 shows a light ray incident on a glass cylinder. What is the angle ? of the ray after it has entered the cylinder?

Problem 49GP If you look at a fish through the corner of a rectangular aquarium you sometimes see two fish, one on each side of the corner, as shown in Figure P18.51. Sketch some of the light rays that reach your eye from the fish to show how this can happen.

Problem 50GP It’s nighttime, and you’ve dropped your goggles into a swimming pool that is 3.0 m deep. If you hold a laser pointer 1.0 m directly above the edge of the pool, you can illuminate the goggles if the laser beam enters the water 2.0 m from the edge. How far are the goggles from the edge of the pool?

Problem 51GP One of the contests at the school carnival is to throw a spear at an underwater target lying flat on the bottom of a pool. The water is 1.0 m deep. You’re standing on a small stool that places your eyes 3.0 m above the bottom of the pool. As you look at the target, your gaze is 30° below horizontal. At what angle below horizontal should you throw the spear in order to hit the target? Your raised arm brings the spear point to the level of your eyes as you throw it, and over this short distance you can assume that the spear travels in a straight line rather than a parabolic trajectory.

Problem 52GP Figure P18.54 shows a meter stick lying on the bottom of a 100-cm-long tank with its zero mark against the left edge. You look into the tank at a 30° angle, with your line of sight just grazing the upper left edge of the tank. What mark do you see on the meter stick if the tank is (a) empty, (b) half full of water, and (c) completely full of water?

Problem 53GP There is just one angle of incidence ? onto a prism for which the light inside an isosceles prism travels parallel to the base and emerges at that same angle ?, as shown in Figure P18.57. a. Find an expression for ? in terms of the prism’s apex angle a and index of refraction n. b. A laboratory measurement finds that ? = 52.2° for a prism that is shaped as an equilateral triangle. What is the prism’s index of refraction?

Problem 55GP A 1.0-cm-thick layer of water stands on a horizontal slab of glass. Light from within the glass is incident on the glass water boundary. What is the maximum angle of incidence for which a light ray can emerge into the air above the water?

Problem 54GP What is the smallest angle u1 for which a laser beam will undergo total internal reflection on the hypotenuse of the glass prism in Figure P18.58?

Problem 56GP The glass core of an optical fiber has index of refraction 1.60. The index of refraction of the cladding is 1.48. What is the maximum angle between a light ray and the wall of the core if the ray is to remain inside the core?

Problem 57GP A swimmer looks upward from the bottom of a 3.0-m-deep swimming pool. The end of the diving board is directly above him, 2.0 m above the water’s surface. How far from the swimmer does the board appear to be?

Problem 58GP A 150-cm-tall diver is standing completely submerged on the bottom of a swimming pool full of water. You are sitting on the end of the diving board, almost directly over her. How tall does the diver appear to be?

Problem 59GP To a fish, the 4.00-mm-thick aquarium walls appear only 3.50 mm thick. What is the index of refraction of the walls?

Problem 60GP A microscope is focused on an amoeba. When a 0.15-mmthick cover glass (n = 1.50) is placed over the amoeba, by how far must the microscope objective be moved to bring the organism back into focus? Must it be raised or lowered?

Problem 62GP A 2.0-cm-tall object is located 8.0 cm in front of a converging lens with a focal length of 10 cm. Use ray tracing to determine the location and height of the image. Is the image upright or inverted? Is it real or virtual?

Problem 61GP A ray diagram can be used to find the location of an object if you are given the location of its image and the focal length of the mirror. Draw a ray diagram to find the height and position of an object that makes a 2.0-cm-high upright virtual image that appears 8.0 cm behind a convex mirror of focal length 20 cm.

Problem 63GP The image produced by a converging lens is typically a different size from the object itself. However, for a lens with focal length f there is one object distance that will yield an image the same size as the object. What is that object distance?

Problem 64GP A near-sighted person might correct his vision by wearing diverging lenses with focal length f = -50 cm. When wearing his glasses, he looks not at actual objects but at the virtual images of those objects formed by his glasses. Suppose he looks at a 12-cm-long pencil held vertically 2.0 m from his glasses. Use ray tracing to determine the location and height of the image.

Problem 65GP A 1.0-cm-tall object is 20 cm in front of a converging lens that has a 10 cm focal length. Use ray tracing to find the position and height of the image. To do this accurately, use a ruler or paper with a grid. Determine the image distance and image height by making measurements on your diagram.

Problem 66GP A 2.0-cm-tall object is 20 cm in front of a converging lens that has a 60 cm focal length. Use ray tracing to find the position and height of the image. To do this accurately, use a ruler or paper with a grid. Determine the image distance and image height by making measurements on your diagram.

Problem 67GP A 1.0-cm-tall object is 7.5 cm in front of a diverging lens that has a 10 cm focal length. Use ray tracing to find the position and height of the image. To do this accurately, use a ruler or paper with a grid. Determine the image distance and image height by making measurements on your diagram.

Problem 68GP A 1.5-cm-tall object is 90 cm in front of a diverging lens that has a 45 cm focal length. Use ray tracing to find the position and height of the image. To do this accurately, use a ruler or paper with a grid. Determine the image distance and image height by making measurements on your diagram.

Problem 69GP A 1.6-m-tall woman stands 2.0 m in front of a convex fun-house mirror with a focal length of 2/3 m. Use ray tracing to determine the location and height of her image.

Problem 70GP A 2.0-cm-tall candle flame is 2.0 m from a wall. You happen to have a lens with a focal length of 32 cm. How many places can you put the lens to form a well-focused image of the candle flame on the wall? For each location, what are the height and orientation of the image?

Problem 71GP A 2.0-cm-diameter spider is 2.0 m from a wall. Determine the focal length and position (measured from the wall) of a lens that will make a half-size image of the spider on the wall.

Problem 72GP Figure P18.75 shows a meter stick held lengthwise along the optical axis of a concave mirror. How long is the image of the meter stick?

Problem 73GP A slide projector needs to create a 98-cm-high image of a 2.0-cm-tall slide. The screen is 300 cm from the slide. a. What focal length does the lens need? Assume that it is a thin lens. b. How far should you place the lens from the slide?

Problem 74GP The writing on the passenger-side mirror of your car says “Warning! Objects in mirror are closer than they appear.” There is no such warning on the driver’s mirror. Consider a typical convex passenger-side mirror with a focal length of -80 cm. A 1.5-m-tall cyclist on a bicycle is 25 m from the mirror. You are 1.0 m from the mirror, and suppose, for simplicity, that the mirror, you, and the cyclist all lie along a line. a. How far are you from the image of the cyclist? b. How far would you have been from the image if the mirror were flat? c. What is the image height? d. What would the image height have been if the mirror were flat? e. Why is there a label on the passenger-side mirror?

Problem 75PP Mirages There is an interesting optical effect you have likely noticed while driving along a flat stretch of road on a sunny day. A small, distant dip in the road appears to be filled with water. You may even see the reflection of an oncoming car. But, as you get closer, you find no puddle of water after all; the shimmering surface vanishes, and you see nothing but empty road. It was only a mirage, the name for this phenomenon. The mirage is due to the different index of refraction of hot and cool air. The actual bending of the light rays that produces the mirage is subtle, but we can make a simple model as follows. When air is heated, its density decreases and so does its index of refraction. Consequently, a pocket of hot air in a dip in a road has a lower index of refraction than the cooler air above it. Incident light rays with large angles of incidence (that is, nearly parallel to the road, as shown in Figure P18.78) experience total internal reflection. The mirage that you see is due to this reflection. As you get nearer, the angle goes below the critical angle and there is no more total internal reflection; the “water” disappears! The pocket of hot air appears to be a pool of water because A. Light reflects at the boundary between the hot and cool air. B. Its density is close to that of water. C. Light refracts at the boundary between the hot and cool air. D. The hot air emits blue light that is the same color as the daytime sky.

Problem 76PP Mirages There is an interesting optical effect you have likely noticed while driving along a flat stretch of road on a sunny day. A small, distant dip in the road appears to be filled with water. You may even see the reflection of an oncoming car. But, as you get closer, you find no puddle of water after all; the shimmering surface vanishes, and you see nothing but empty road. It was only a mirage, the name for this phenomenon. The mirage is due to the different index of refraction of hot and cool air. The actual bending of the light rays that produces the mirage is subtle, but we can make a simple model as follows. When air is heated, its density decreases and so does its index of refraction. Consequently, a pocket of hot air in a dip in a road has a lower index of refraction than the cooler air above it. Incident light rays with large angles of incidence (that is, nearly parallel to the road, as shown in Figure P18.78) experience total internal reflection. The mirage that you see is due to this reflection. As you get nearer, the angle goes below the critical angle and there is no more total internal reflection; the “water” disappears! Which of these changes would allow you to get closer to the mirage before it vanishes? A. Making the pocket of hot air nearer in temperature to the air above it B. Looking for the mirage on a windy day, which mixes the air layers C. Increasing the difference in temperature between the pocket of hot air and the air above it D. Looking at it from a greater height above the ground

Problem 77PP Mirages There is an interesting optical effect you have likely noticed while driving along a flat stretch of road on a sunny day. A small, distant dip in the road appears to be filled with water. You may even see the reflection of an oncoming car. But, as you get closer, you find no puddle of water after all; the shimmering surface vanishes, and you see nothing but empty road. It was only a mirage, the name for this phenomenon. The mirage is due to the different index of refraction of hot and cool air. The actual bending of the light rays that produces the mirage is subtle, but we can make a simple model as follows. When air is heated, its density decreases and so does its index of refraction. Consequently, a pocket of hot air in a dip in a road has a lower index of refraction than the cooler air above it. Incident light rays with large angles of incidence (that is, nearly parallel to the road, as shown in Figure P18.78) experience total internal reflection. The mirage that you see is due to this reflection. As you get nearer, the angle goes below the critical angle and there is no more total internal reflection; the “water” disappears! If you could clearly see the image of an object that was reflected by a mirage, the image would appear A. Magnified. B. With up and down reversed. C. Farther away than the object. D. With right and left reversed.