Photoelectrons are emitted from two similar metal plates when wavelengths λ₁ and λ₂ are incident on them ( λ₁ = 1.5λ₂). If maximum kinetic energy of emitted photoelectrons is E₁ and E₂ respectively then (a) E₁ < 2E₂/3 (b) E₁ = 2E₂/3 (c) E₁ = E₂/3 (d) E₁ = 2E₂

Answer: (a). E = (hc)/(λ) - φ; with λ₁ = 1.5λ₂: E₁ = 2/3(hc)/(λ₂) - φ. 2E₂/3 = 2/3(hc)/(λ₂) - (2φ)/(3) Since φ > (2φ)/(3), E₁ < 2E₂/3. So the answer is (a).

Photoelectrons are emitted from two similar metal plates when… | MHT CET 2026 (11 Apr, Shift 2)

Q26MHT CET 2026 · 11 APR · SHIFT 2Medium

Photoelectric Effect: Einstein's Equation

Photoelectrons are emitted from two similar metal plates when wavelengths $\lambda_1$ and $\lambda_2$ are incident on them ( $\lambda_1 = 1.5\lambda_2$ ). If maximum kinetic energy of emitted photoelectrons is $E_1$ and $E_2$ respectively then

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Answer: (a)

$E = \frac{hc}{\lambda} - \phi$ ; with $\lambda_1 = 1.5\lambda_2$ : $E_1 = \frac{2}{3}\frac{hc}{\lambda_2} - \phi$ .
$\frac{2E_2}{3} = \frac{2}{3}\frac{hc}{\lambda_2} - \frac{2\phi}{3}$
Since $\phi > \frac{2\phi}{3}$ , $E_1 < \frac{2E_2}{3}$ .
So the answer is (a).

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