The period-luminosity relation for Cepheid variables was discovered in 1908 by:
A) William Herschel.
B) Henrietta Leavitt.
C) Harlow Shapley.
D) Heber Curtiss.
E) Edwin Hubble.
B
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Suppose you live in the United States and you see a crescent moon in your evening sky tonight. What will a friend in South America see tonight?
A) Your friend will see a gibbous moon. B) Your friend will also see a crescent moon. C) Your friend will see a first-quarter moon. D) Your friend won't see the Moon tonight because it is up only in the morning.
A constant volume and mass of helium gas at 27°C is heated so that the pressure of the gas doubles. What is the new temperature of the gas in Celsius degrees?
The energy level diagram for hydrogen
The energy of the most energetically possible photon emitted is
a.
1.5 eV.
b.
1.9 eV.
c.
3.4 eV.
d.
10.2 eV.
e.
13.6 eV.
The light-sensitive cells in our eyes that allow us to see color are called ________.
Fill in the blank(s) with the appropriate word(s).