How many second-magnitude stars would be needed in a close cluster to match the light intensity of a first-magnitude star?
A) about 2.5
B) 2
C) about 10
D) about 0.4, or 1/2.5

Question

Quizplus · Accepted Answer

The magnitude scale is logarithmic, with a difference of 1 magnitude corresponding to a brightness factor of about 2.5. Therefore, it takes about 2.5 second-magnitude stars to equal the brightness of one first-magnitude star.

How Many Second-Magnitude Stars Would Be Needed in a Close