Question

The sun delivers ${10}^3{\text{Wm}}^{-2}$ of electromagnetic flux to the earth’s surface. The total power that is incident on a roof of dimensions $8\text{m}\times 20\text{m}$ will be-

• A. $2.56\times {10}^4\text{W}$
• B. $6.4\times {10}^5\text{W}$
• C. $4.0\times {10}^5\text{W}$
• D. $1.6\times {10}^5\text{W}$

Answer 1

The correct option is D $1.6\times {10}^5\text{W}$

Given,

$I={10}^3{\text{Wm}}^{-2};A=8\times 20{\text{m}}^2$

As we know, Intensity is given by,

$I=\frac{\text{Energy}}{\text{area}\times t}=\frac{\text{Power}}{\text{Area}}$

$1000=\frac{P}{8\times 20}$

$P=1.6\times {10}^5\text{W}$

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Hence, $\left(D\right)$ is the correct answer.