Note: The word "brightness" is used in this quiz to mean how bright a star appears in the sky. The word "luminosity" refers to how bright a star is (independent of its distance from us).
1.What happens when a stationary observer views a moving light
source?
a. the speed, frequency, and wavelength of the light all change
b. the frequency of the light doesn't change, but its wavelength and
speed do
c. the speed of the light doesn't change, but its frequency and wavelength
do
d. the wavelength and brightness of the light change, and the speed and
frequency stay the same
2. Because of the Doppler shift, a light source emits light that is
_________ when it is moving ____________ than when it is at rest.
a. redshifted (at longer wavelengths); away from us
b. redshifted (at longer wavelengths); across our line of sight
c. redshifted (at longer wavelengths); toward us
d. blueshifted (at shorter wavelengths); in any direction
3. What is a parsec?
a. a unit of time equal to about 3.26 million seconds
b. a unit of angle equal to 1/3600 of a degree
c. the distance light travels in one year
d. the distance at which the parallax angle is 1 arcsecond
4. The trigonometric parallaxes of Stars A and B are measured. Star A has
a parallax angle of 1 arcsecond, and Star B has a parallax angle of 0.5
arcsecond. Which of the following is true?
a. Star A is twice as far away as Star B
b. Star B is twice as far away as Star A
c. Star A is twice as large as Star B
d. Star B is twice as large as Star A