Question

The sum radiates electromagnetic energy at the rate of $4.0 \times 10^{26} W$. Its radius is $7 \times 10^{8} m$. The intensity of sun light at the solar surface is

• A. $4.54 \times 10^{8} Wm ^{-2}$
• B. $5.09 \times 10^{-8} Wm ^{-2}$
• C. $3.00 \times 10^{8} Wm ^{-2}$
• D. $10^{8} Wm ^{-2}$

Answer 1

Answer: (A)

As, Intensity $=\frac{\text { Power }}{\text { Arca }}$
$=\frac{4.0 \times 10^{26}}{4 \pi r^{2}}$
$=\frac{4 \times 10^{26}}{4 \times \frac{22}{7} \times\left(7 \times 10^{8}\right)^{2}}$
$=4.54 \times 10^{8} Wm ^{-2}$