Astronomy Chapter 5

If two objects are the same size but one object is 3 times hotter than the other object, the hotter object emits

81 times more energy.

When an atom absorbs a photon containing energy, any of the following can happen except which?

An electron moves form an upper energy level to a lower one.

Which of the following statements about electrons is not true?

Electrons orbit the nucleus rather like planets orbiting the Sun.

True or false: Energy and power are different words for the same thing.

False

True or false: Grass is green because it absorbs green light, reflecting all other colors.

False

How are wavelength, frequency, and energy related for photons of light?

Longer wavelengths mean lower frequency and lower energy.

Suppose you see two stars: a blue star and a red star. Which of the following can you conclude about the two stars? Assume that no Doppler shifts are involved. (Hint: Think about the laws of thermal radiation.)

The blue star has a hotter surface temperature than the red star.

You observe a distant galaxy. You find that a spectral line normally found in the visible part of the spectrum is shifted toward the infrared. What do you conclude?

The galaxy is moving away from you.

You observe the same spectral line in two stars that are identical in every way except that one rotates faster than the other. How does the spectral line differ between the two?

The line in the faster rotating star is broader.

If one object has a large redshift and another object has a small redshift, what can we conclude about these two objects?

The one with the large redshift is moving away from us faster than the one with the small redshift.

If we observe one edge of a planet to be redshifted and the opposite edge to be blueshifted, what can we conclude about the planet?

The planet is rotating.

From laboratory measurements, we now that a particular spectral line formed by hydrogen appears at a wavelength of 121.6 nanometers (nm). The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 121.8 nm. What can we conclude?

The star is moving away from us.

From laboratory measurements, we know that a particular spectral line formed by hydrogen appears at a wavelength of 486.1 nanometers (nm). The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 485.9 nm. What can we conclude?

The star is moving toward us.

We can learn a lot about the properties of a star by studying its spectrum. All of the following statements are true except one. Which one?

The total amount of light in the spectrum tells us the star's radius.

Which of the following statements about X rays and radio waves is not true?

X rays travel through space faster than radio waves.

Compared to the volume of its nucleus, the volume of an atom is about

a trillion times greater.

From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation?

gamma rays, X rays, ultraviolet, visible light, infrared, radio

The spectra of most galaxies show redshifts. This means that their spectral lines

have wavelengths that are longer than normal.

When an atom loses an electron, it becomes

ionized.

Sublimation is the process in which

molecules go from the solid phase to the gas phase.

The study of energy levels in atoms is called

quantum mechanics

Thermal radiation is defined as

radiation produced by a hot object

From lowest energy to highest energy, which of the following correctly orders the different categories of electromagnetic radiation?

radio, infrared, visible light, ultraviolet, X rays, gamma rays

We can see each other in the classroom right now because we

reflect visible light.

Suppose you built a scale-model atom in which the nucleus was the size of a tennis ball. About how far would the cloud of electrons extend?

several kilometers

The wavelength of a wave is

the distance between two adjacent peaks of the wave.

Can the Doppler shift be measured with invisible light?

yes