Question:

A $5$ watt source emits monochromatic light of wavelength $5000\,?$. When placed $0.5\, m$ away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved to a distance of $1.0 \,m$, the number of photo electrons liberated will:

Updated On: Jul 19, 2024
  • be reduced by a factor of 8
  • be reduced by a factor of 16
  • be reduced by a factor of 2
  • be reduced by a factor of 4
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The Correct Option is D

Solution and Explanation

No. of photoelectrons or intensity $\propto \frac{1}{(\text { distance })^{2}}$
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Concepts Used:

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Electronic Emission

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Photoelectric Effect

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Heisenberg’s Uncertainty Principle

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