Answer:
I₂ = 25 W / m²
Explanation:
Intensity is defined as the relationship between power and area
I = P / A
the power emitted by the sun is constant
P = I A
for the two points of interest
I₁ A₁ = I₂ A₂
energy is distributed on the surface of a sphere
A = 4π R²
I₁ R₁² = I₂ R₂²
I₂ = [tex]\frac{R_1^2}{R_2^2} \ I_1[/tex]
let's calculate
I₂ = [tex]\frac{R^2}{(4R)^2} \ 400[/tex]
I₂ = 25 W / m²