Chapter 5 Test Your Understandings
Two stars are of equal luminosity. Star A is 3 times as far from you as star B. Star A appears ______ star B.
1/9 as bright as
What is the surface temperature of a star that has a peak wavelength of 290 nm?
10,000K
Why is an iron atom a different element from a sodium atom?
An iron atom has more protons in its nucleus than a sodium atom has.
If the Sun instantaneously stopped giving off light, what would happen on Earth?
Earth would get dark 8 minutes later.
Star A and star B appear equally bright in the sky. Star A is twice as far away from Earth as star B. How do the luminosities of stars A and B compare?
Star A is 4 times as luminous as star B.
How does the speed of light in a medium compare to the speed in a vacuum?
The speed in the medium is always slower than the speed in a vacuum.
When an electron moves from a higher energy level in an atom to a lower energy level,
a photon is emitted.
The temperature of an object has a very specific meaning as it relates to the object's atoms. A high temperature means that the atoms
are moving very fast.
In Figure 5.15, the red photons come from the transition from E3 to E2. These photons will have the ____ wavelengths because they have the ______ energy compared to the other photons.
longest; least
As a blackbody becomes hotter, it also becomes __________ and __________.
more luminous; bluer
When less energy radiates from a planet, its ______________ increases until a new ______________ is achieved.
temperature; equilibrium
When a boat moves through the water, the waves in front of the boat bunch up, while the waves behind the boat spread out. This is an example of
the Doppler effect.
If a planet is in thermal equilibrium,
the amount of energy leaving equals the amount of energy arriving.
Which of the following factors does not directly influence the temperature of a planet?
the size of the planet
