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MHT CET · Physics · Dual Nature of Matter

When a photosensitive surface is irradiated by light of wavelength ' \(\lambda_1\) ' and ' \(\lambda_2\) ', maximum kinetic energies of emitted photoelectrons are ' \(E_1\) ' and ' \(E_2\) ' respectively. The work function of photosensitive surface is

  1. A \(\frac{\left(\lambda_1 E_1-\lambda_2 E_2\right)}{\left(\lambda_2-\lambda_1\right)}\)
  2. B \(\frac{\left(\lambda_1 E_1+\lambda_2 E_2\right)}{\left(\lambda_2-\lambda_1\right)}\)
  3. C \(\frac{\left(\lambda_1 E_2-\lambda_2 E_1\right)}{\left(\lambda_2-\lambda_1\right)}\)
  4. D \(\frac{\left(\lambda_1 E_2+\lambda_2 E_1\right)}{\left(\lambda_2-\lambda_1\right)}\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(\frac{\left(\lambda_1 E_1-\lambda_2 E_2\right)}{\left(\lambda_2-\lambda_1\right)}\)

Step-by-step Solution

Detailed explanation

\( \begin{aligned} & \mathrm{E}_1=\frac{\mathrm{hc}}{\lambda_1}-\mathrm{W} \\ & \mathrm{E}_2=\frac{\mathrm{hc}}{\lambda_2}-\mathrm{W} \\ & \mathrm{E}_1 \lambda_1+\mathrm{W} \lambda_1=\mathrm{E}_2 \lambda_2+\mathrm{W} \lambda_2 \\ & \mathrm{~W}=\frac{\mathrm{E}_1 \lambda_1-\mathrm{E}_2 \lambda_2}{\lambda_2-\lambda_1} \end{aligned} \)