A laser beam can be focussed 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 focussed beam will be
A
B
C
D
None of these
Text Solution
Verified by ExpertsThe correct answer is:
B
Area through which the energy of beam passes
∴ ∴ 
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