Gamma rays have a very small

Gamma rays have a very small 

A) energy.
B) frequency.
C) mass.
D) wavelength.


Answer: D

Suppose you are listening to a radio station that broadcasts at a frequency of 97 Mhz (megahertz). Which of the following statements is true?

Suppose you are listening to a radio station that broadcasts at a frequency of 97 Mhz (megahertz). Which of the following statements is true? 

A) The radio waves from the radio station are causing electrons in your radio's antenna to move up and down 97 million times each second.
B) The radio waves from the radio station have a wavelength of 97 million meters.
C) The "radio waves" received by your radio are not light waves like those we talk about in astronomy, but rather are a special type of sound wave.
D) The radio station broadcasts its signal with a power of 97 million watts.


Answer: A

Which of the following statements is true of green grass?

Which of the following statements is true of green grass? 

A) It absorbs red light and emits green light.
B) It absorbs red light and reflects green light.
C) It transmits all colors of light except green.
D) It means the lawn is healthy.


Answer: B

Suppose you have a 100-watt light bulb that you leave turned on for one minute. How much energy does it use?

Suppose you have a 100-watt light bulb that you leave turned on for one minute. How much energy does it use? 

A) 6,000 joules
B) 6,000 watts
C) 100 watts
D) 100 joules


Answer: A

You observe a distant galaxy. You find that a spectral line of hydrogen that is shifted from its normal location in the visible part of the spectrum into the infrared part of the spectrum. What can you conclude?

You observe a distant galaxy. You find that a spectral line of hydrogen that is shifted from its normal location in the visible part of the spectrum into the infrared part of the spectrum. What can you conclude? 

A) The galaxy is moving away from you.
B) The galaxy is moving towards you.
C) The galaxy has very weak gravity.
D) The galaxy is made purely of hydrogen.


Answer: A

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

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

A) have wavelengths that are longer than normal.
B) always are in the red part of the visible spectrum.
C) have wavelengths that are shorter than normal.
D) have a higher intensity in the red part of the spectrum.


Answer: A

Suppose you want to know the chemical composition of a distant star. Which piece of information is most useful to you?

Suppose you want to know the chemical composition of a distant star. Which piece of information is most useful to you? 

A) The peak energy of the star's thermal radiation.
B) The Doppler shift of the star's spectrum.
C) The wavelengths of spectral lines in the star's spectrum.
D) Whether the star's spectrum has more emission lines or more absorption lines.


Answer: C

According to the laws of thermal radiation, hotter objects emit photons with

According to the laws of thermal radiation, hotter objects emit photons with

A) a lower average frequency.
B) a shorter average wavelength.
C) a lower average energy.
D) a higher average speed.


Answer: B

Thermal radiation is defined as

Thermal radiation is defined as

A) radiation with a spectrum whose shape depends only on the temperature of the emitting object.
B) radiation produced by an extremely hot object.
C) radiation that is felt as heat.
D) radiation in the form of emission lines from an object.


Answer: A

Suppose you look at a spectrum of visible light by looking through a prism or diffraction grating. How can you decide whether it is an emission line spectrum or an absorption line spectrum?

Suppose you look at a spectrum of visible light by looking through a prism or diffraction grating. How can you decide whether it is an emission line spectrum or an absorption line spectrum? 

A) An emission line spectrum consists of bright lines on a dark background, while an absorption line spectrum consists of dark lines on a rainbow background.
B) An emission line spectrum consists of a long bright line, while an absorption line spectrum consists of a long dark line.
C) The only way to decide is to make a graph of the intensity of the light at every wavelength, and then analyze the graph carefully.
D) The emission line spectrum is produced by electrons jumping up in energy level, while the absorption line spectrum is produced by electrons jumping down in energy level.


Answer: A