Which of these is dependent on distance?

• Brightness

• Luminosity

Which is the LEAST bright?

• A star with the sun's luminosity 10 ly away

• A star with half the sun's luminosity 5 ly away

• A star with the sun's luminosity 5 ly away

• A star with a quarter of the sun's luminosity 3 ly away

Which of these emits the most energetic photons?

• A radio broadcast tower

• The lights in this room

• A microwave oven

• A doctor's x-ray machine

Answer explanation

Out of all of these, x-rays have the shortest wavelength or highest frequency, making that light the most energetic.

Hotter objects produce...

• Mostly infrared light

• Redder light

• Temperature is not related to light emission

• Bluer light

Hotter objects produce...

• Fewer photons

• More photons

• More gasses that emit photons

• Temperature is not related to the number of emitted photons

Why are blackbodies called "blackbodies?"

• The first one discovered was black in color

• They don't emit any light

• They are usually obscured in some way, making them look black

• They reflect little to no light

Which one of these deals with the peak wavelength of a blackbody?

• Stefan-Boltzman law

• Law of blackbodies

• Wien's Law

• Law of peak wavelengths of blackbodies

According to the Stefan-Boltzman law, how are radius and temperature related to luminosity?

Which answer has two stars of the same luminosity?

• Star 1 is twice as large as star 2
  
  Star 2 is twice as hot as star 1

• Star 1 is twice as large as star 2
  
  The stars have the same temperature
  
  The distance between us and star 2 is half that of the distance between us and star 1

• Star 1 is four times larger than star 2
  
  Star 2 is twice temperature of star 1

• None of these

The spectrum of the sun would not look like this because

• The sun is not a black body.

• The sun is a black body, but it doesn't emit visible lights.

• Since the sun is much closer to the Earth other than any of stars, it would show much brighter spectrum.

• Some of the photons from the sun will be absorbed by the sun's cooler gas and the earth's atmosphere.

Answer explanation

Gas atoms on the atmosphere of the sun and the earth will absorb photons that has the same energy as the electrons' orbital transitional energy.