Deck 3: Light and Matter: the Inner Workings of the Cosmos

Question 1

Wave energy can only be transmitted through a material medium.

Answer 1

False

Question 2

The spectral lines of each element are distinctive to that element, whether we are looking at emission or absorption lines.

Answer 2

True

Question 3

Observations in the X- ray portion of the spectrum are routinely done from the surface of the Earth.

Answer 3

False

Question 4

According to Wein's law, the larger the blackbody, the shorter its peak wavelength.

Question 5

The shorter a wave's wavelength, the greater its energy.

Question 6

Radio waves, visible light, and X- rays are all types of electromagnetic radiation.

Question 7

The greater the disturbance of the medium, the higher the amplitude of the wave.

Question 8

As white light passes through a prism, the red (longer) wavelengths bend less than the blue (shorter) wavelengths, so forming the rainbow of colors.

Question 9

Doubling the temperature of a blackbody will double the total energy it radiates.

Question 10

A blue star has a higher surface temperature than a red star.

Question 11

If a new wave arrives on shore every two seconds, then its frequency is 2 Hz.

Question 12

An emission line results from an electron falling from a higher to lower energy orbital around its atomic nucleus.

Question 13

Changing the electric field will have no effect on the magnetic fields of a body.

Question 14

According to Wein's law, the higher the surface temperature of a star, the redder its color.

Question 15

As they move through space, the vibrating electrical and magnetic fields of a light wave must move perpendicular to each other.

Question 16

An absorption line spectrum, with dark lines crossing the rainbow of the continuum, is produced by a low- density hot gas.

Question 17

While gravity is always attractive, electromagnetic forces are always repulsive.

Question 18

The frequency of a water wave gives us its height.

Question 19

In blackbody radiation, the energy is radiated uniformly in every region of the spectrum, so the radiating body appears black in color.

Question 20

As a star's temperature increases, the frequency of peak emission also increases.

Question 21

When an electron in a hydrogen atom drops from the second to the first excited energy state it emits a bright red emission line called hydrogen alpha.

Question 22

Which of these is the same for all forms of electromagnetic (E- M) radiation in a vacuum?

A) frequency
B) wavelength
C) speed
D) amplitude
E) photon energy

Question 23

The speed of light in a vacuum is

A) 186,000 miles per hour.
B) h = E/c.
C) 300,000 km/sec.
D) 768 km/hour.
E) none of the above.

Question 24

The broader the spectral line, the higher the pressure of the gas that is creating it.

Question 25

The Doppler effect can reveal the rotation speed of a star by the splitting of the spectral lines.

Question 26

The larger the redshift, the faster the distant galaxy is rushing toward us.

Question 27

In the Doppler effect, a redshift of spectral lines shows us the source is receding from us.

Question 28

Spectral lines are produced when an electron makes a transition from one energy state to another.

Question 29

Medium A blocks more of a certain wavelength of radiation than medium B. Medium A has a higher

A) opacity.
B) transparency.
C) clarity.
D) seeing.
E) albedo.

Question 30

You would perceive a change in a visible light wave's amplitude as a change in its color.

Question 31

If a fire truck's siren is rising in pitch, it must be approaching us.

Question 32

The two forms of electromagnetic (E- M) radiation that experience the least atmospheric opacity are

A) microwaves and radio waves.
B) X and gamma radiation.
C) ultraviolet and infrared waves.
D) visible light and infrared waves.
E) visible light and radio waves.

Question 33

In the Bohr model of the atom, an electron can only exist in specific, well- defined energy levels.

Question 34

A wave's velocity is the product of the

A) frequency times the wavelength of the wave.
B) frequency times the period of the wave.
C) period times the energy of the wave.
D) amplitude times the frequency of the wave.
E) amplitude times the wavelength of the wave.

Question 35

Spectroscopy of a star can reveal its temperature, composition, and line- of- sight motion.

Question 36

The Zeeman effect reveals the presence of strong magnetic fields by the splitting of spectral lines.

Question 37

If a wave's frequency doubles and its speed stays constant, its wavelength

A) is now 4× longer.
B) is halved.
C) is also doubled.
D) becomes 16× longer.
E) is unchanged, as c is constant.

Question 38

Which of these is NOT a form of electromagnetic radiation?

A) X- rays in the doctor's office
B) DC current from your car battery
C) ultraviolet causing a suntan
D) light from your camp fire
E) radio signals

Question 39

The radiation our eyes are most sensitive to is the color

A) black at 227 nm.
B) violet at 7,000 Angstroms.
C) red at 6563 Angstroms.
D) yellow- green at about 550 nm.
E) blue at 4,321 nm.

Question 40

Consider this diagram. Which statement is true?

A) The amplitude is 8 and the wavelength is 6.
B) The amplitude is 8 and the wavelength is 12.
C) The amplitude is 6 and the wavelength is 4.
D) The amplitude is 4 and the wavelength is 12.
E) The amplitude is 4 and the wavelength is 6.

Question 41

The element first found in the Sun's spectrum, then on Earth 30 years later, is

A) technicum.
B) hydrogen.
C) helium.
D) aluminum.
E) solarium.

Question 42

Which of these is emitted when an electron falls from a higher to lower orbital?

A) a neutrino
B) a positron
C) a graviton
D) a photon
E) another electron

Question 43

In Bohr's model of the atom, electrons

A) can be halfway between orbits.
B) are not confined to specific orbits.
C) are spread uniformly through a large, positive mass.
D) move from one orbit to the next orbit in many small steps.
E) only make transitions between orbits of specific energies.

Question 44

What is the name of the temperature scale that places zero at the point where all atomic and molecular motion ceases?

A) Ransom
B) Fahrenheit
C) Kelvin
D) Centigrade
E) Celsius

Question 45

For hydrogen, the transition from the first to third excited state produces

A) a blue green absorption line.
B) an ultraviolet line.
C) a red emission line.
D) an infrared line.
E) a violet emission line.

Question 46

The Sun's observed spectrum is

A) a continuum with absorption lines.
B) only absorption lines on a black background.
C) a continuum with no lines, as shown by the rainbow.
D) a continuum with emission lines.
E) only emission lines on a black background.

Question 47

A jar filled with gas is placed directly in front of a second jar filled with gas. Using a spectroscope to look at one jar through the other you observe dark spectral lines. The jar closest to you contains

A) gas at the same temperature as the other jar.
B) the cooler gas.
C) gas at very high pressure.
D) the hotter gas.
E) the exact same gas as the other jar.

Question 48

In a hydrogen atom, a transition from the 2nd to the 1st excited state will produce

A) the bright red Balmer alpha emission line.
B) three different emission lines.
C) a dark absorption line.
D) an ultraviolet spectral line.
E) no emission line.

Question 49

Electromagnetic radiation

A) has only the properties of waves.
B) can behave both as a wave and as a particle.
C) can only travel in a dense medium.
D) is the same as a sound wave.
E) has nothing in common with radio waves.

Question 50

What is true of a blackbody?

A) Its energy is not a continuum.
B) It has a complete absence of thermal energy.
C) Its energy peaks at the wavelength determined by its temperature.
D) If its temperature doubled, the peak in its radiation curve would be doubled in wavelength.
E) It appears black to us, regardless of its temperature.

Question 51

A frequency of one hundred means the wave is vibrating one hundred million times per second; this is a typical carrier frequency for FM (frequency modulation) radio.

A) millihertz
B) gigahertz
C) hertz
D) megahertz
E) kilohertz

Question 52

Increasing the temperature of a blackbody by a factor of 3 will increase its energy by a factor of

A) 3.
B) 6.
C) 9.
D) 12.
E) 81.

Question 53

According to the Zeeman effect, the splitting of a sunspot's spectral lines is due to

A) temperature variations.
B) a Doppler shift.
C) their radial velocity.
D) their rapid rotation.
E) their magnetic fields.

Question 54

The observed spectral lines of a star are all shifted towards the red end of the spectrum. Which statement is true?

A) The star has a radial velocity towards us.
B) The second law of Kirchhoff explains this.
C) The star is not rotating.
D) This is an example of the photoelectric effect.
E) This is an example of the Doppler effect.

Question 55

If a star was the same size as our Sun, but was 81 times more luminous, it must be

A) twice as hot as our Sun.
B) three times hotter than the Sun.
C) four times hotter than the Sun.
D) nine times hotter than the Sun.
E) 81 times hotter than the Sun.

Question 56

If a source of light is approaching us at 3,000 km/sec, then all its waves are

A) blueshifted by 1%.
B) blueshifted out of the visible spectrum into the ultraviolet.
C) redshifted by 1%.
D) redshifted out of the visible into the infrared.
E) not affected, as c is constant regardless of the direction of motion.

Question 57

In the Kelvin scale, absolute zero lies at

A) - 373 degrees C.
B) 273 degrees C.
C) zero K.
D) Both A and B are correct.
E) Both A and C are correct.

Question 58

In general, the spectral lines of molecules are

A) less complex than those of atoms.
B) only absorption lines.
C) more complex than those of atoms.
D) the same as the atoms they contain.
E) nonexistent.

Question 59

The total energy radiated by a blackbody depends on

A) the fourth root of its temperature.
B) the cube of its temperature.
C) the square of its temperature.
D) the fourth power of its temperature.
E) the square root of its temperature.

Question 60

If the rest wavelength of a certain line is 600 nm, but we observe it at 594 nm, then

A) the source is getting 1% hotter as we watch.
B) the source is approaching us at 0.1% of the speed of light.
C) the source is receding from us at 10% of the speed of light.
D) the source is approaching us at 1% of the speed of light.
E) the source is spinning very rapidly, at 1% of the speed of light.

Question 61

The product of the wavelength times the frequency of a wave is its .

Question 62

The common element discovered in the Sun's spectrum before it was found here is
.

Question 63

The Sun's blackbody curve peaks in the portion of the spectrum.

A) ultraviolet
B) X- ray
C) radio
D) infrared
E) visible

Question 64

Stefan's law notes that total energy radiated is proportional to the _ power of the temperature of the blackbody.

Question 65

An electron has a electric charge.

Question 66

A wave with a period of .01 seconds has a frequency of Hz.

Question 67

Stars that appear blue or white in color are than our yellow Sun.

Question 68

The energy of the photon depends on its .

Question 69

Fraunhofer was the German astronomer who first noted _ lines in the Sun's spectrum.

Question 70

According to Wein's law, the wavelength of the peak energy will be if the temperature of the blackbody is doubled.

A) doubled
B) quadrupled
C) quartered
D) unchanged
E) halved

Question 71

The common element with bright red, blue- green, and violet emission lines is

A) hydrogen.
B) nitrogen.
C) oxygen.
D) carbon.
E) helium.

Question 72

The most energetic photons are

A) infrared.
B) radio.
C) X- rays.
D) gamma rays.
E) visible.

Question 73

In electromagnetic waves, the electric and magnetic fields vibrate to each other.

Question 74

When an electron moves from a lower to a higher energy state, a photon is .

Question 75

A dense, hot body will give off a(n) spectrum.

Question 76

A featureless spectrum, such as a rainbow, is said to be .

Question 77

The distance from a wave's crest to its undisturbed position is the _ .

Question 78

An FM station broadcasts at a frequency of 100 MHz. The wavelength of its carrier wave is
.

Question 79

A wave with a frequency of 2 Hz will have a period of .

Question 80

Knowing the peak emission wavelength of a blackbody allows you to determine its
.