Light with an energy flux of 18 ; W/cm^2 fall | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(D) The total energy $U$ falling on the surface is given by the product of energy flux,area,and time.$U = (18 \; W/cm^2) 	imes (20 \; cm^2) 	imes (3

Vedclass · Accepted Answer

$1.2 	imes 10^{-6} \; N$

Vedclass · Answer

(D) The total energy $U$ falling on the surface is given by the product of energy flux,area,and time.$U = (18 \; W/cm^2) 	imes (20 \; cm^2) 	imes (30 	imes 60 \; s)$$U = 18 	imes 20 	imes 1800 \; J = 6.48 	imes 10^5 \; J$For a non-reflecting (completely absorbing) surface,the momentum $p$ delivered by the light is given by $p = U/c$,where $c = 3 	imes 10^8 \; m/s$ is the speed of light.$p = \frac{6.48 	imes 10^5 \; J}{3 	imes 10^8 \; m/s} = 2.16 	imes 10^{-3} \; kg \cdot m/s$The average force $F$ exerted on the surface is the rate of change of momentum:$F = \frac{p}{t} = \frac{2.16 	imes 10^{-3} \; kg \cdot m/s}{1800 \; s}$$F = 1.2 	imes 10^{-6} \; N$

Light with an energy flux of $18 \; W/cm^2$ falls on a non-reflecting surface at normal incidence. If the surface has an area of $20 \; cm^2$,find the average force exerted on the surface during a $30$ minute time span.

Similar Questions

$A$ flashlight of intensity $9 \, W/cm^2$ illuminates a perfectly reflective surface of area $300 \, cm^2$. The average force exerted on the surface due to the incident light photons is

If the total energy transferred to a surface in time $t$ is $6.48 \times 10^5 \,J$, then the magnitude of the total momentum delivered to this surface for complete absorption will be:

An electromagnetic wave of intensity $1400 \, W/m^2$ falls on a metal surface of area $1.5 \, m^2$ and is completely absorbed by it. Find the force exerted by the beam.

$A$ parallel beam of light is incident normally on a plane surface absorbing $50\%$ of the light and reflecting the rest. If the incident beam carries $90 \text{ W}$ of power,the force exerted by it on the surface is ($C = 3 \times 10^8 \text{ m/s}$ is the velocity of light in air).

What is the force exerted on a mirror of area $40 \, cm^2$ when an $EM$ wave of intensity $6 \, W/m^2$ is incident on it?

Vedclass Test Series

Exam Paper Generator

Online Exam Module