Sun light falls normally on a surface of area 36,cm ^{2} and exerts an average force of 7.2 × 10^{-

English

Gujarati

Hindi

8.Electromagnetic waves

medium

Sun light falls normally on a surface of area $36\,cm ^{2}$ and exerts an average force of $7.2 \times 10^{-9}\,N$ within a time period of $20$ minutes. Considering a case of complete absorption, the energy flux of incident light is.

A

$25.92 \times 10^{2}\,W / cm ^{2}$

B

$8.64 \times 10^{-6}\,W / cm ^{2}$

C

$6.0\,W / cm ^{2}$

D

$0.06\,W / cm ^{2}$

(JEE MAIN-2022)

Solution

$\frac{I}{C} \times$ area $=$ force

$\frac{I}{C} \times 36 \times 10^{-4}=7.2 \times 10^{-9}$

$I =\frac{7.2 \times 10^{-9} \times 3 \times 10^{8}}{36 \times 10^{-9} \times 10}$

$=\frac{6 \times 10^{-1}}{10^{-3}}$

$I =6 \times 10^{2} \frac{ w }{ m ^{2}}$

$=0.06 \frac{ w }{ cm ^{2}}$

Standard 12

Physics

Share

Similar Questions

The electric field part of an electromagnetic wave in vacuum is

$E = 3.1\,NC^{-1}\,cos\,[\,(1.8\,rad\,m^{-1})\,y + (5.4\times 18^8\,rad\,s^{-1})\,t\,]\,\hat i$

The wavelength of this part of electromagnetic wave is……$m$

easy

The electric field of an electromagnetic wave in free space is represented as $\vec{E}=E_0 \cos (\omega t-k z) \hat{i}$.The corresponding magnetic induction vector will be :

hard

(JEE MAIN-2024)

A lamp emits monochromatic green light uniformly in all directions. The lamp is $3%$ efficient in converting electrical power to electromagnetic waves and consumes $100\,W $ of power. The amplitude of the electric field associated with the electromagnetic radiation at a distance of $10m$ from the lamp will be……..$V/m$

medium

Radiations of intensity $0.5\,\,W/{m^2}$ are striking a metal plate. The pressure on the plate is

easy

The magnetic field in a plane electromagnetic wave is given by $=2 \times 10^{-7} \sin \left(0.5 \times 10^3 x+1.5 \times 10^{11} t\right)$. This electromagnetic wave is ………

medium