A 2   m W laser operates at a wavelength of   500   n m . The number of photons that will be…

A 2 mW laser operates at a wavelength of  500 nm . The number of photons that will be emitted per second is:
[Given Planck's constant h=6.6×10-34 J s, speed of light  c=3.0×108 m/s ]
  1. 1.5×1016
  2. 5×1015
  3. 2×1016
  4. 1×1016

Solution

P=2 mW
λ=500 nm
Number of photons will be emitted per second is,
n=Phcλ=2×10-3×500×10-96.6×10-34×3×108
=5×1015

Asked in: JEE Main 2019 (10 Apr Shift 2)

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