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A laser can be focused on an area = square of its $\lambda$. For a He-Ne laser having $\lambda$= 6328 $\mathring{A}$ and radiating at 1 mW, find the intensity of its focused beam.
written 6.7 years ago by gravatar for neeta.vanage neeta.vanage • 860 modified 2.7 years ago by gravatar for pedsangini276 pedsangini276 • 4.8k

Subject :- Applied Physics 2

Topic :- Lasers

Difficulty :- Medium
engineering physics
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written 6.6 years ago by gravatar for neeta.vanage neeta.vanage • 860 modified 6.6 years ago by gravatar for saurabhsingh saurabhsingh • 40

$$ $$ $ A = \lambda ^2$,

$\lambda =6328 * 10^{-16} m$,

$P = 1* 10^{-3} W \\ I = P/A \\ A = (6328 *10^{-10} )^2 \\ I = 2.49 * 10^9 watts/m^2 \\ $

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