Suppose that two identical stars (they have the same total light output) are located so that star a is at a distance of 5 pc and star b is at a distance of 25 pc from earth. how will star b appear, compared with star a?

star B will appear 1/25 = 0.04 times compared to star A

star b will look smaller from star A

Explanation:

star A is at a distance of 5 pc

star B is at a distance of 25 pc

How will star B appear, compared with star A?

the inverse square law of light for apparent brigthness, b =

b= L/(4πd²)

where, L is the luminiosity = light output

d = distance

L₁/(4πd₁²) = L₂/(4πd₂²)

since L, is constant

d₁² = d₂²

5² = 25²

[5/25]² = [1/5]² = 1/25

star B will appear 1/25 = 0.04 times compared to star A

star b will look smaller from star A

thermal energy is the answer