Suppose that two identical stars (having the same total light output or luminosity)are located such that star A is at a distance of 5 pc and star B is at a distance of 25 pc.How will star B appear,compared to star A?
A) 1/22 as bright
B) 1/25 as bright
C) 1/20 as bright
D) 1/5 as bright

Question

Quizplus · Accepted Answer

The apparent brightness of a star is inversely proportional to the square of its distance. Since both stars have the same luminosity, the only factor affecting their apparent brightness is their distance. Using the inverse square law, we can calculate the ratio of the apparent brightness of star B to star A: (25/5)^2 = 5^2 = 25. This means that star B will appear 1/25 as bright as star A. Therefore, the best choice is B.

Suppose That Two Identical Stars (Having the Same Total Light