The emission rate of electromagnetic waves physics question?

Question

The Sun emits electromagnetic waves (including light) equally in all directions. The intensity of the waves at the Earth's upper atmosphere is 1.4 kW/m^2. At what rate does the Sun emit electromagnetic waves? (In other words, what is the power output?)

Answer 1

Good question!

Let the r be the radius of the Sun
Let R be the distance from the Sun's center to the surface of the earth. We have a sphere of radius r within a sphere of radius R. The surface area is
S=4piR^2

Let P be the amount of radiation (power) on the surface of the Earth while p (power) leaving the surface of the Sun.

P/S=p/s= 1.4 kW/m^2
Pt=Total power= (P/S)S
Pt=4 pi (P/S) R^2
Pt= 4 x pi x 1400 ( 146 E+9 )^2
Pt = 3.75 E+26 Watts