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MHT CET 2025 (25 Apr, Shift 1) · Photoelectric Effect: Einstein's Equation

Photoelectric Effect: Einstein's Equation question from MHT CET 2025 (25 Apr, Shift 1)

Q30MHT CET 2025 · 25 APR · SHIFT 1Easy

Photoelectric Effect: Einstein's Equation

Sodium and copper have work functions 2.3 eV and 4.5 eV respectively. The ratio of threshold wavelength of sodium to that of copper is nearest to

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Answer: (d)

$\lambda_0 = \dfrac{hc}{\phi}$ , so $\lambda_0 \propto \dfrac{1}{\phi}$
$\dfrac{\lambda_{Na}}{\lambda_{Cu}} = \dfrac{4.5}{2.3} \approx 1.96 \approx 2$
So the answer is (d) $2:1$ .

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