Chapter 7: Light

When does total internal reflection occur in water? -when the incident ray is 49° -at the critical angle for water -when the angle of refraction reaches 90°

*ALL OF THE ABOVE* -when the incident ray is 49° -at the critical angle for water -when the angle of refraction reaches 90°

Why do astronauts in orbit around the earth see a black sky with stars that do not twinkle but see a blue Earth? -Light is absorbed by space, but reflected from Earth. -Earth has an atmosphere, which scatters blue light; the sky where they are does not. -They are too far from the sun, which makes the sky black, but are relatively close to Earth. -Light from stars in space is not reflected, so stars do not twinkle and the sky is black.

-Earth has an atmosphere, which scatters blue light; the sky where they are does not.

Why does a highway sometimes appear wet on a hot summer day when it is not wet? -Hot air near the road refracts light upward into cooler air above, which is interpreted as reflected light. -Warm air has a higher index of refraction than cooler air, which reflects light. -The road actually is wet with a thin layer of moisture, which evaporates when you approach. -Moisture in the air is reflecting the surface of a large body of water.

-Hot air near the road refracts light upward into cooler air above, which is interpreted as reflected light.

What conditions are necessary for two light waves to form an interference pattern of bright lines and dark areas? -In phase light waves travel different distances from two slits to a screen. -Out of phase light waves produce bright zones. -In phase light waves produce dark zones.

-In phase light waves travel different distances from two slits to a screen.

What happens to light that is absorbed by matter? -Part becomes internal kinetic energy and part is lost. -It is partly absorbed and partly transmitted. -It is completely absorbed and gives up all its energy. -It ceases to exist.

-It is completely absorbed and gives up all its energy.

Why does the intensity of reflected light appear to change if you tilt your head from side to side while wearing polarizing sunglasses? -Reflected light is polarized in a horizontal direction; sunglasses have vertical transmission axes. -Polarizing sunglasses have horizontally oriented transmission axes. -Reflected light has the same polarized orientation as polarized sunglasses. -Sunglasses absorb vertically oriented polarized light.

-Reflected light is polarized in a horizontal direction; sunglasses have vertical transmission axes.

How can you tell if a pair of sunglasses is polarizing or not? -Rotate the lens over a lens of a second known polarizing pair; light should be transmitted, and then absorbed when one is rotated 90°. -Look at a blue sky with the sunglasses and rotate them; you will observe no changes. -Wear the glasses, then move your head from side to side while looking at reflected glare and you will observe no change. -A sunset should appear more blue through polarizing sunglasses.

-Rotate the lens over a lens of a second known polarizing pair; light should be transmitted, and then absorbed when one is rotated 90°.

What determines if an electromagnetic wave emitted from an object is a visible light wave or a wave of infrared radiation? -Visible light is from room-temperature objects, infrared warmer. -Infrared is emitted near absolute zero, visible light from cooler objects. -Visible light comes from non-luminous and cold objects. -The energy available for accelerating charged particles determines this.

-The energy available for accelerating charged particles determines this.

Based on the energy of different colors of light, what color should be used for warning lights? -blue -orange -red -green

-blue

Which color of light carries more energy? -orange -blue -green -red

-blue

Which of the following stars has the highest temperature? -bluish -reddish -yellowish -orange-red

-bluish

What model of light does the photoelectric effect support? The photoelectric effect is explained -by a particle model. -only by a wave model. -by the light ray model. -only by refraction and reflection. -None of the above

-by a particle model.

What model of light does the polarization of light support? Polarized light is explained -by electrons absorbing energy. -only by a wave model. -by the light ray model. -only by refraction and reflection.

-only by a wave model.

Why does total internal reflection occur more in a diamond than in other gemstones? -no critical angle -the critical angle is about 49° -small critical angle -large critical angle

-small critical angle

The color difference in stars is a result of the relationship between the color and -size. -temperature. -composition. -age.

-temperature.