Ch. 26 Flashcards
Two slabs with parallel faces are made from different types of glass. One blue glass and one gray glass. A ray of light travels through air and enters each lab at the same angle of incidence. Which slab has the greater index of refraction?
The gray glass
Light traveling through air is incident on a flat piece of glass at an 35 degree angle of incidence and enters the glass at an angle of refraction theta(glass). Suppose that a layer of water is added on top of the glass. Then the light travels through air and is incident on the water at the 35 degree angle of incidence. Does the light enter the glass at the same angle of refraction theta(glass), as it did when the water was not present?
Yes
Two identical containers, one filled with water (n= 1.33) and the other with benzene (n= 1.50) are viewed from directly above. Which container appears to have a greater depth of fluid?
The one filled with water
When an observer peers over the edge of a deep, empty, metal bowl on a kitchen table, he does not see the entire bottom surface. Therefore, a small object lying on the bottom is hidden from view, but the object can be seen when the bowl is filled with liquid A. When the bowl is filled with liquid B, however, the object remains hidden from view. Which liquid has the greater index of refraction?
Liquid A
A man is fishing from a dock, using a bow and arrow. To strike a fish that he sees beneath the water, where should he aim?
Somewhat below the fish
A man is fishing from a dock. He is using a laser gun that emits an intense beam of light. To strike a fish that he sees beneath the water, where should he aim?
Directly at the fish
Two rays of light converge to a point on a screen. A thick plate of glass with parallel surfaces is placed in the path of these converging light, with the parallel surfaces parallel to the screen. What will the point of convergence do?
Move away from the glass plate
A shallow swimming pool has a constant depth. A point source of light is located in the middle of the bottom of this pool and emits light in all directions. However, no light exits the surface of the water except through a relatively small circular area that is centered on and directly above the light source. Why does the light exit the water through such a limited area?
The critical angle for water-air interface is 48.8 degrees. Any light emitted at an angle greater than 48.8 degrees with respect to the vertical is incident on the surface at an angle exceeding the critical angle. It is totally internally reflected and doesn’t exit the water.
The ray within the glass slab is traveling from a medium with a larger refractive index toward a medium with a smaller refractive index. It is possible, for theta, less that 90 degrees, that the ray within the glass will experience total internal reflection at the glass-air interface?
No
You are sitting by the shore of a lake on a sunny and windless day. When are your Polaroid sunglasses most effective in reducing the glare of the sunlight reflected from the lake surface? When the angle of incidence of the sunlight on the lake is ___.
Somewhere between 90 and 0 degrees
Two blocks, made from the same transparent material, are immersed in different liquids. One is in blue liquid, one in pink liquid. A ray strikes each block at the same angle of incidence. With liquid has the greater index of refraction?
Blue liquid
A beam of violet-colored light is propagating in crown glass. When the light reaches the boundary between the glass and the surrounding air, the beam is totally reflected back into the glass. What happens if the light is red and has the same angle of incidence theta1 at the glass-air interface as does the violet-colored light?
Depending on the value for theta1, red light may not be totally reflected, and some of it may be refracted into the air.
A beacon in a lighthouse is to produce a parallel beam of light. The beacon consists of a light source and a converging lens. Where should the light source be placed?
At the focal point of the lens
Is it possible for a lens to behave as a converging lens when surrounded by air but to behave as a diverging lens when surrounded by another medium?
Yes
A converging lens is used to produce a real image. A piece of black tape is then placed over the upper half of the lens. Which one of the following statements is true concerning the image that results with the tape in place?
The image is of the entire object, although it’s brightness is reduced since fewer rays produce it
A spherical mirror and a lens are immersed in water. Compared to the way they work in air, which one do you expect will be more affected by the water?
The lens
An object is located at a distance do in front of a lens. The lens has a focal length f and produces an upright image that is twice as tall as the object. What kind of lens is it, and what is the object distance?
Converging lens
do = (1/2)f
In an old movie a photographic film negative is introduced as evidence in a trial. The negative shows an image of a house that no longer exists. The verdict depends on knowing exactly how far above the ground a window ledge was. The distance between the ground and the ledge on the negative can be measured. What additional information is needed to calculate h0?
Both do and f are needed
Two people who wear glasses are camping. One is nearsighted, and the other is farsighted. Whose glasses may be useful in starting a fire by concentrating the suns rays into a small region at the focal point of the lens used in the glasses?
The glasses of the farsighted person, since they use converging lenses
Suppose that a person with a near point of 26cm is standing in front of a plane mirror. How close can he stand to the mirror and still see himself I focus?
13 cm
To a swimmer underwater, objects look blurred. However, goggles that keep the water away from the eyes allow their swimmer to see objects in sharp focus. Why?
Light normally passes from air (n=1.00) into the cornea (n=1.38), at which time most of the eyes refraction of the light occurs
If water (n=1.33) replaces air, the similarity of the index of refraction of water to that of the cornea reduces the eyes normal refraction and causes blurred vision.
Goggles preserve the air-cornea boundary.
When glasses use diverging lenses to correct for nearsightedness or converging lenses to correct for farsightedness, the eyes of the person wearing the glasses lie between the lenses and their focal points. When you look at the eyes of this person, they do not appear to have their normal size. Which one of the following describes what you see?
The converging lenses make the eyes appear larger, and the diverging lenses make the eyes appear smaller.
A bird-watcher sees the following three raptors in the air at the distances indicated:
- A kestrel (wing span: 0.58m at a distance of 21m)
- a bald eagle (wing span: 2.29m at a distance of 95m)
- a red-tailed hawk (wing span: 1.27m at a distance of 41m).
Rank the raptors in descending order according to the angular size seen by the bird-watcher.
Hawk, kestrel, eagle
Who benefits more from using a magnifying glass, a person whose near point is located at a distance away from the eyes of 75cm or 25cm?
75cm
