Chapter 11 Review

Video Review

Key Concept Summary

TA Summary

Vocabulary

Match the experiment with what property it demonstrates about light.

Single spot of light after passing through double-slit experiment

Light spreading out when handkerchief is held up to light.

Interference pattern created by the double-slit experiment.

Photoelectric effect.

Picture formed by low intensity light.

The way a digital cameras operate.

Match the definition and the term.

Carrier wave modulated by changing the frequency

The ejection of electrons from metals when light is shined on the metal's surface

Possessing both wave and particle properties.

A particle of light. It possesses energy, frequency, and wavelength but neither mass nor charge.

A series of bright lines separated by dark areas.

Carrier wave modulated by changing the amplitude.

Radiation originating in a varying electromagnetic field, such as visible light, radio waves, x-rays, and gamma rays.

True/False

Sharp shadows ultimately prove that light doesn't diffract and is therefore a particle.

True False

Light is an electromagnetic disturbance spread throughout space according to electromagnetic laws.

True False

Galileo accurately predicted the speed of light using two lanterns.

True False

The photoelectric effect shows that the frequency of light determines whether or not an electron will be discharged.

True False

Analysis

Traveling at the speed of light, Diana and Anna go on a trip that takes them 10 light seconds. How far did they travel?

350,000 km 2,997,925 km 6,230,543 km 1,876,232 km

The difference between blue light and red light is that

red light has more energy per photon red light has a higher speed blue light has a higher speed red light has a longer wavelength blue light has a longer wavelength

One night Sam looks at a street light through the screen of a window or door. He carefully observes the apparent image. The image reveals light streaks extend outward from a central bright spot. The outward streaks are also seen to consist of a series of light and dark spaces. When the same light is viewed without looking through a screen, no streaks are seen. The presence and pattern of the streaks are due to

diffraction and interference refraction and interference diffraction and refraction reflection and refraction reflection and diffraction

The wavelength of red light (700 nanometers) is longer than the wavelength of violet light (400 nanometers). Which of the following statements is true?

The photon energy of red light is highest because the wavelength is longest. The photon energy of both colors is the same because light travels with a constant velocity. The photon energy of violet light is highest because the frequency is highest. The photon energy of the light waves depends on the wave amplitudes which are not given. The photon energies of both colors are small, which make it difficult for the eye to see.

Which of the following is true regarding red and blue light?

They both travel at different speeds from one another in a vacuum. Only red light creates an interference pattern. Only blue light creates a diffraction pattern. Photons from blue light have more energy. Both blue light and red light have the same wavelength.

Which of the following is the best description of a photon?

A particle with mass and positive charge. A particle without mass and with positive charge. A particle without mass and with negative charge. A particle with mass and negative charge. A particle with mass and no charge. A particle without mass and with no charge.

The energy of a photon is related to its

Amplitude Wave speed Frequency

When sunlight passes through a large opening, such as a door or window, it makes a bright spot about the size of the opening. When light passes through a very small opening, such as a pin hole, it spreads out over an area much larger than the size of the opening. This occurs because light

has colors. has electrical charge. carries energy. has particle properties. has wave properties.

Light from a laser shines on a pair of closely spaced slits and then fall on a screen. No attempt is made to detect the light until it hits the screen. Which of the following best represents the resulting image on the

a single narrow band about as narrow as a single slit. a single fuzzy band that is wider than the combined width of the slits. a single dot. two narrow bands about the width of each slit. a series of bright and dark bands.

What does the experiment described in the previous problem demonstrate about the behavior of light?

Light has colors. Light has electrical charge. Light carries energy. Light has particle properties. Light has wave properties.

Extremely dim light shines on a pair of closely spaced slits and then fall on a screen. No attempt is made to detect the light until it hits the screen. What happens to the pattern produced as the light gets dimmer and dimmer?

The pattern stays basically the same shape, but gets dimmer. The pattern stays basically the same shape, but gets fuzzier. The pattern stays basically the same shape, but gets narrower. The pattern stays basically the same shape, but gets speckled, like it is made up of dots. Changing the brightness of the light doesn’t change the pattern at all.

A single photon is incident on a pair of closely spaced slits. Which of the following best represents the image seen on a distant screen?

a single narrow band about as narrow as a single slit. a single fuzzy band that is wider than the combined width of the slits. a single dot. two narrow bands that are a little wider than the width of each slit. a series of bright and dark bands.

There are experiments that show that light has wave properties.

True False

There are experiments that show that light has particle properties.

True False

The photoelectric effect shows that light has ________ properties.

wave particle

The interference of light shows that light has __________ properties.

wave particle

Which of the following types of electromagnetic radiation travels at the fastest speed?

Red light Blue light Gamma rays AM radio The speed is the same for all of the above.

How does the energy of a single photon of red light compare to that of a single photon of blue light?

The red photon has more energy. The blue photon has more energy. The red and blue photons have the same energy.

If a single photon is shot through a double slit apparatus, does it behave as a wave or a particle?

wave particle both

Two slits are arranged, one above of the other. A photon passes through the slits, and makes a spot near the bottom of a distant screen. What is true?

This photon went through the top slit. This photon went through the bottom slit. The photon went through either the top or the bottom slit, but you can't tell which. The photon went through both slits at once.

If you wished to do an experiment on blackbody radiation, which of the following would make the best black body?

An incandescent light bulb. A fluorescent light bulb. A glow-in-the-dark sticker. a laser.

What happens to the amount of red light an object emits as it is heated to higher and higher temperatures?

It increases. It decreases. It remains the same.

If light behaved only as a wave, and the ultraviolet catastrophe didn't occur, what color would the sun be?

the same color it is now, yellow. more red. more blue. invisible because it would only produce ultraviolet light.

If a photon of yellow light is split in half, what do you get?

Two photons, one red, one green Two photons, both yellow Two photons at half the frequency This is impossible, you can't split photons.

A Helium-Neon laser produces a single frequency of red light. If the power of the laser is increased from 100mW to 200mW, what happens to the energy of the photons?

It increases. It decreases. It remains the same.

If Plank's constant were much larger, what would happen?

Light's wave behavior would be more apparent. Light's particle behavior would be more apparent. Light's behavior wouldn't be affected.

A 100 Watt single frequency UV lamp is being used to knock electrons off of a metal surface by the photoelectric effect. If the power of the lamp is doubled to 200Watts, what happens to the energy of the electrons?

It increases. It decreases It remains the same

It increases It decreases It remains the same

A 100-Watt single frequency UV lamp is being used to knock electrons off of a metal surface by the photoelectric effect. If the power of the lamp remains the same, but the frequency is doubled, what happens to the energy of the released electrons?

It increases. It decreases. It remains the same.

A 100 Watt UV light is being used to knock electrons off of a metal surface by the photoelectric effect. If the power of the lamp remains the same, but the frequency is doubled, what happens to the number of electrons released?

It increases. It decreases. It remains the same.

Recently there have been claims in the news that VLF radiation, (electromagnetic waves with frequencies lower than radio waves), from fluorescent lights can cause cancer by knocking electrons out of your DNA. Could VLF radiation do this?

Yes, if you were exposed to it long enough. Yes, if you were close enough to the light. Yes, if the light were bright enough. No, never.

A double slit apparatus is designed for microwaves with a 1 cm wavelength. If a low intensity source is used, what is the size of the spot the individual microwave photons would make on a scintillator screen?

bigger than the spots made by visible light. about the same size as the spots made by visible light. smaller than the spots made by visible light.

Free Response

How does the double-slit experiment show that light has interference properties?
List the different types of electromagnetic radiation in order from the lowest frequency to the highest frequency.
What four characteristics does light exhibit that shows its wave nature?
Using the principle of non-contradiction, explain and justify what the chapter concludes about the nature of light.
How do scientists think that light travels through space?
Why do scientists use light years as a unit of measurement when speaking of large distances in space?
Light is described as a transverse wave. However, it travels through empty space where there are no molecules to move perpendicularly to the wave. How can we call it a transverse wave?
If a door between a brightly lit room and a dark one is left slightly ajar, there will be a band of light on the floor. If the door is slowly closed, what happens to this band of light? Why?
When very dim light is used to make a photograph, what happens to the image? If very dim light was used in a double slit experiment, what would happen to the image? How does a double slit experiment done with dim light show the dual nature of photons?
How did luminiferous ether filling space allow scientists to continue considering light as a wave?
Why does a diffraction grating cause colors in light to separate? In what order should colors appear?
Upon seeing the sharp image of shadow, Newton concluded that light was not a wave. He did not know the wavelength of light. Why might this knowledge have changed his conclusion?
In a photoelectric effect experiment using visible light, what happens when you change the brightness of the light source? What happens when you change the frequency of the light source? How does the photoelectric effect prove that light behaves as a particle? What would have happened if light were just a wave?
Light transports energy like the mechanical waves described in Chapter 10 but with a profound difference. Contrast the understanding of energy in mechanical waves with the understanding of energy in light.
Scientists speak of light traveling through a field that inhabits empty space. Would you call this an hypothesis, theory, law, or model? Why?