When light of wavelength ' $\lambda$ ' is incident on a photosensitive surface, photons of power '…

When light of wavelength ' $\lambda$ ' is incident on a photosensitive surface, photons of power ' $\mathrm{P}$ ' are emitted. The number of photon ' $\mathrm{n}$ ' emitted in time ' $\mathrm{t}$ ' is [$\mathrm{h}$ = Planck's constant, $\mathrm{c}=$ velocity of light in vacuum]
  1. $\frac{\mathrm{hc}}{\mathrm{P} \lambda \mathrm{t}}$
  2. $\frac{\mathrm{P} \lambda}{\mathrm{htc}}$
  3. $\frac{\mathrm{P} \lambda \mathrm{t}}{\mathrm{hc}}$
  4. $\frac{\mathrm{hP}}{\lambda \mathrm{tc}}$

Solution

Power, $\mathrm{P}=\frac{\text { Energy }}{\mathrm{t}}=\frac{\mathrm{nhc}}{\lambda \mathrm{t}}$ $\therefore \mathrm{n}=\frac{\mathrm{p} \lambda \mathrm{t}}{\mathrm{hc}}$

Asked in: MHT CET 2021 (20 Sep Shift 2)

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