Let K1 and K2 be the maximum kinetic energies of photo-electrons emitted when two monochromatic beams of wavelength λ 1 and λ 2, respectively are incident on a metallic surface. If λ 1 = 3 λ 2 then: (a) K₁ > K₂/3 (b) K₁ < K₂/3 (c) K₁ = K₂/3 (d) K₂ = K₁/3

Answer: (b). K₁ = (hc)/(3λ₂) - φ and K₂/3 = (hc)/(3λ₂) - φ/3. Since φ > φ/3, K₁ < K₂/3. So the answer is (b).

Let K1 and K2 be the maximum kinetic energies of photo-electrons… | JEE Main 2022 (28 Jun, Shift 2)

Q99JEE Main 2022 · 28 JUN · SHIFT 2Medium

Photoelectric Effect: Einstein's Equation

Let K1 and K2 be the maximum kinetic energies of photo-electrons emitted when two monochromatic beams of wavelength $\lambda$ 1 and $\lambda$ 2, respectively are incident on a metallic surface. If $\lambda$ 1 = 3 $\lambda$ 2 then:

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Answer: (b)

$K_1 = \frac{hc}{3\lambda_2} - \phi$ and $\frac{K_2}{3} = \frac{hc}{3\lambda_2} - \frac{\phi}{3}$ .
Since $\phi > \frac{\phi}{3}$ , $K_1 < \frac{K_2}{3}$ .
So the answer is (b).

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