A laser beam with wavelength lambda = 633 nm | vedclass

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

Question

(B) The power of the laser beam is $P = 3 \ mW = 3 	imes 10^{-3} \ W$.The cross-sectional area is $A = 3 \ mm^2 = 3 	imes 10^{-6} \ m^2$.For a perfe

Vedclass · Accepted Answer

$6.6 	imes 10^{-6} \ N/m^2$

Vedclass · Answer

(B) The power of the laser beam is $P = 3 \ mW = 3 	imes 10^{-3} \ W$.The cross-sectional area is $A = 3 \ mm^2 = 3 	imes 10^{-6} \ m^2$.For a perfectly reflecting surface with normal incidence,the force exerted by the radiation is given by $F = \frac{2P}{c}$,where $c = 3 	imes 10^8 \ m/s$ is the speed of light.$F = \frac{2 	imes 3 	imes 10^{-3}}{3 	imes 10^8} = 2 	imes 10^{-11} \ N$.The pressure $p$ is defined as force per unit area: $p = \frac{F}{A}$.$p = \frac{2 	imes 10^{-11} \ N}{3 	imes 10^{-6} \ m^2} = \frac{2}{3} 	imes 10^{-5} \ N/m^2 = 0.666... 	imes 10^{-5} \ N/m^2 = 6.66 	imes 10^{-6} \ N/m^2$.Rounding to two significant figures,the pressure is $6.6 	imes 10^{-6} \ N/m^2$.

$A$ laser beam with wavelength $\lambda = 633 \ nm$ has a power of $3 \ mW$. If the cross-sectional area of the beam is $3 \ mm^2$,what is the pressure exerted by the beam on a surface? (Assume the surface is a perfect reflector and the light is incident normally.)

Similar Questions

$A$ light bulb of power $100 \ W$ is placed at the centre of a hollow sphere of radius $10 \ cm$. If $66\%$ of the energy is converted into light,then the pressure exerted by the light on the surface of the sphere will be (Assume the surface of the sphere to be perfectly absorbing).

$50\, W/m^2$ energy density of sunlight is normally incident on the surface of a solar panel. Some part of incident energy $(25\%)$ is reflected from the surface and the rest is absorbed. The force exerted on $1\, m^2$ surface area will be close to $(c = 3 \times 10^8\, m/s)$.

$A$ radiation of energy $E$ falls on a perfectly reflecting surface. The momentum transferred to the surface is (let $c$ be the speed of light).

$A$ 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).

An object is placed in a medium of refractive index $3$. An electromagnetic wave of intensity $6 \times 10^8 \ W/m^2$ falls normally on the object and it is absorbed completely. The radiation pressure on the object would be (speed of light in free space $= 3 \times 10^8 \ m/s$): (in $N/m^2$)

Vedclass Test Series

Exam Paper Generator

Online Exam Module