Help with astronomy homework?

[minnesotafan22]

If the surface temperature of the Sun doubled while its size remained the same

it would radiate twice as much energy.
it would radiate four times as much energy.
it would radiate eight times as much energy.
it would radiate sixteen times as much energy.
it would radiate the same amount of energy.

 

[Jeremy]

L=4(pi)(r^2)(sigma)(T^4)

Plug in 2r and see what happens.