GRE Subject Test: Physics : Astrophysics

Study concepts, example questions & explanations for GRE Subject Test: Physics

varsity tutors app store varsity tutors android store

All GRE Subject Test: Physics Resources

33 Practice Tests Question of the Day Flashcards Learn by Concept

Example Questions

Example Question #1 : Astrophysics

If the temperature of a blackbody doubles, what occurs to the wavelength of maximum emission? 

Possible Answers:

It doubles. 

No change.

It is quartered. 

It is halved. 

It quadruples. 

Correct answer:

It is halved. 

Explanation:

This is an application of Wein's Law that states the following:

, where  is the wavelength of maximum emission of the object (measured in ), and  is the temperature in . Since the wavelength and the temperature are inversely proportional, if we double the temperature, we must cut the wavelength by the same proportion. Therefore, the temperature must be halved.   

Example Question #2 : Astrophysics

By what factor will the energy emitted each second off the surface of a blackbody change if the the temperature of the object is tripled? 

Possible Answers:

Correct answer:

Explanation:

Stefan-Boltzmann's equation for a blackbody states:

, where  is the energy emitted each second,  is the Stefan-Boltzmann constant, and  is the temperature of the blackbody. Therefore, if we triple the temperature, the energy will increase by a factor of 

Example Question #3 : Astrophysics

Using the kinetic theory of gas, what is the fundamental property of a planet that dictates if it is able to retain an atmosphere?

Possible Answers:

Energy

Temperature

Mass

Number of moons

Magnetic field strength

Correct answer:

Mass

Explanation:

The kinetic theory of gas states:

. Whenever the velocity of the individual gas particles is larger than the escape speed of the planet, 

, the gas particles will leak into space and deplete the atmosphere. The physical property that determines this is the mass of the planet. 

All GRE Subject Test: Physics Resources

33 Practice Tests Question of the Day Flashcards Learn by Concept
Learning Tools by Varsity Tutors

Incompatible Browser

Please upgrade or download one of the following browsers to use Instant Tutoring: