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(B) The area $A$ on which the laser beam is focused is equal to the square of its wavelength $\lambda^2$.Given, $\lambda = 632.8 \, nm = 6.328 	imes

Vedclass · Accepted Answer

$2.5 	imes 10^9 \, W/m^2$

Vedclass · Answer

(B) The area $A$ on which the laser beam is focused is equal to the square of its wavelength $\lambda^2$.Given, $\lambda = 632.8 \, nm = 6.328 	imes 10^{-7} \, m$.Area $A = \lambda^2 = (6.328 	imes 10^{-7})^2 \approx 4.0 	imes 10^{-13} \, m^2$.The power $P$ of the laser is $1 \, mW = 10^{-3} \, W$.The intensity $I$ is given by the formula $I = \frac{P}{A}$.Substituting the values: $I = \frac{10^{-3} \, W}{4.0 	imes 10^{-13} \, m^2} = 0.25 	imes 10^{10} \, W/m^2 = 2.5 	imes 10^9 \, W/m^2$.

$A$ laser beam can be focused on an area equal to the square of its wavelength. $A$ $He-Ne$ laser radiates energy at the rate of $1 \, mW$ and its wavelength is $632.8 \, nm$. The intensity of the focused beam will be:

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