Astronomy Quiz for A2

A hydrogen line has a wavelength of 486 nm in the lab, but 501 nm from a distant galaxy. What is the change in wavelength?

• 13 nm
• 18 nm
• 20 nm
• 15 nm

• Surface temperature
• Radius of the star
• Luminosity
• Temperature

Calculate the frequency of the line observed at 501 nm.

How do emission lines of hydrogen differ when observed from distant galaxies?

• The lines appear at the same wavelength
• The lines have a shorter wavelength
• The lines have a longer wavelength
• The lines disappear completely

Hubble's law implies that as galaxies move away from us, their recession speeds will:

• Decrease over time
• Remain constant
• Increase with distance
• Decrease with distance

Hubble's law states that the speed of recession of a galaxy is proportional to its:

• Distance
• Mass
• Luminosity
• Temperature

The inverse square law for radiant flux density is given by which equation?