PHYSICS · Single correct · A Level · Physics · Astrophysics · Astrophysics
Problem
Of the following, the best definition for *apparent brightness* is
(1) the total energy emitted by a star in 1 s.
(2) the total power per unit area emitted by a star.
(3) the ratio of a star's output power to that of the Sun.
(4) the power per unit area received at the Earth's surface from a star.