B.1 Review MCQ 2

What is a black body?

• An object that reflects all energy

• A theoretical object that absorbs all energy from all wavelengths of light

• A real object that emits only visible light

• An object that only absorbs ultraviolet light

What does a black body in thermal equilibrium emit?

• Only visible light

• Only infrared radiation

• Black body radiation containing all wavelengths of light

• Only ultraviolet light

Which objects are very close approximations to black bodies?

• Planets

• Stars

• Moons

• Comets

What does Wien’s Law state about the absolute temperature of a star?

• It is directly proportional to the wavelength of maximum radiation

• It is inversely proportional to the wavelength of maximum radiation

• It is unrelated to the wavelength of maximum radiation

• It is equal to the wavelength of maximum radiation

How is the luminosity of a black body measured?

• In joules

• In watts

• In lumens

• In candelas

What is the luminosity of a black body directly proportional to?

• The volume of the star

• The surface area of the star

• The mass of the star

• The density of the star

To what power is the absolute temperature of a star raised in relation to its luminosity?

• Second power

• Third power

• Fourth power

• Fifth power

What is the apparent brightness of a star?

• The total energy emitted by the star

• How bright it appears to an observer

• The color of the star

• The size of the star

How is the apparent brightness of a star measured?

• In watts per square meter

• In lumens per square meter

• In joules per square meter

• In candelas per square meter

What is the apparent brightness of a star directly proportional to?

• The distance from the observer

• The star’s luminosity

• The star’s mass

• The star’s volume