The sun radiates electromagnetic energy at the rate of $3.9 \times 10^{26}W$. Its radius is $6.96 \times 10^8m$.

if the distance from the sun to the earth is 1.5 x  10¹¹ m, then the intensity of sunlight on earth's surface will be-(in W/m²)

1.38 x 10³    

$ I_{earth} = \frac{P}{4\pi r_{earth}^2} = \frac{3.9\times 10^{26}}{4\times 3.14\times 2.25\times 10^{11}} = 1.38\times 10^3W/m^2$