Question

The sun radiates electromagnetic energy at the rate of $3.9\times 10^{26} \, W.$ Its radius is $6.96\times 10^{8} \, m.$ The intensity of sunlight at the solar surface will be - (in $W \, m^{- 2}$ )

• A. $1.4\times 10^{4}$
• B. $2.8\times 10^{5}$
• C. $4.2\times 10^{6}$
• D. $6.4\times 10^{7}$

Answer 1

Answer: (D)

$I_{s u r f a c e}=\frac{P}{A}=\frac{3.9 \times \left(10\right)^{26}}{4 \times 3.14 \times \left(6.96\right)^{2} \times \left(10\right)^{16}}$
$=6.4\times 10^{7} \, W \, m^{- 2}$