26.1

26.2

26.3

26.4

Shadow DiffuseShadowShadow

26.5

26.6

umbra

penumbra

26.7

26.8

26.9

-- Questions --

MULTIPLE CHOICEMULTIPLE CHOICE.

Choose the one alternative that best completes the statement or

answers the question.answers the question.

26.10

1) Compared to ultraviolet waves, the wavelength of infrared waves is A) the same. B) shorterB) shorter. C) longer.

) h l i l li h i i id l i h l2) When ultraviolet light is incident upon glass, atoms in the glass A) resonate. B) pass the light energy along practically undiminished. ) p g gy g p yC) freely absorb and re-emit most of the ultraviolet light. D) are forced into vibration.

26.11

3) The natural frequency of the atoms in glass is in the A) infrared part of the spectrum. B) ultraviolet part of the spectrumB) ultraviolet part of the spectrum. C) visible part of the spectrum.

) h h h i i h4) The Earth's atmosphere is transparent to most waves in the A) infrared part of the spectrum. B) ultraviolet part of the spectrum. ) p pC) visible part of the spectrum. D) entire electromagnetic spectrum.

26.12

5) Most of the electromagnetic spectrum consists of visible light. A) True B) FalseB) False

6) Which of these electromagnetic waves has the shortest wavelength? ) l i lA) ultraviolet waves

B) X-rays C) infrared waves )D) light waves E) radio waves

26.13

7) The speed of light in the void between molecules in glass is A) the same as its speed in a vacuum. B) more than its speed in a vacuumB) more than its speed in a vacuum. C) less than its speed in a vacuum.

) h i f h il f d d8) The size of the pupil of your eye depends on A) the brightness of light in the room. B) the time of day. ) yC) your mood. D) the temperature of the room. E) two of theseE) two of these.

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9) What is the frequency of an electromagnetic wave that has a wavelength of 300,000 km? A) more than 1 HzA) more than 1 Hz B) 1 Hz C) less than 1 Hz

10) The moon would be at its fullest just before the time of a A) lunar eclipse. ) pB) solar eclipse. C) both of these. D) none of theseD) none of these.

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11) Infrared waves are often called heat waves because they A) induce resonance in molecules and increase internal energy in a substancesubstance. B) are the predominant waves emitted by the sun. C) emanate from relatively hot sources.

) i f f i l h h f i ibl li hD) consist of frequencies lower than those of visible light. E) are absorbed rather than reflected by the skin.

12) If an electron vibrates up and down 1000 times each second, it generates an electromagnetic wave having a

A) period of 1000 sA) period of 1000 s. B) frequency of 1000 Hz. C) wavelength of 1000 km. D) d f 1000 /D) speed of 1000 m/s. E) wavelength of 1000 m.

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13) If the sun were to disappear right now, we wouldn't know about it for 8 minutes because it takes 8 minutes A) for light to travel from the sun to the EarthA) for light to travel from the sun to the Earth. B) for the sun to disappear. C) to operate receiving equipment in the dark.

) ll f hD) all of these. E) none of these.

14) Compared to its average speed in air, the average speed of a beam of light in glass is A) lessA) less. B) the same. C) more.

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15) Information-carrying nerves are connected to the retina at A) the fovea. B) the corneaB) the cornea. C) the iris. D) the periphery.

) h bli dE) the blind spot.

16) Consider light energy that is momentarily absorbed in glass and then ) g gy y gre-emitted. Compared to the absorbed light, the frequency of the re-emitted light is

A) slightly lessA) slightly less. B) considerably less. C) slightly more. D) id blD) considerably more E) the same.

26.18

-- Answers --

MULTIPLE CHOICEMULTIPLE CHOICE.

The one alternative that best completes the statement or

answers the question.answers the question.

26.19

Chapter 26

1) Answer: C1) Answer: C 2) Answer: A 3) Answer: B

)4) Answer: C 5) Answer: B 6) Answer: B )7) Answer: A 8) Answer: E 9) Answer: B9) Answer: B 10) Answer: A 11) Answer: A 12) A B12) Answer: B 13) Answer: A 14) Answer: A

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)15) Answer: E 16) Answer: E