K₁ and K₂ be the maximum kinetic energies of photoelectrons emitted from a surface of a given material for the light of wavelength λ₁ and λ₂, respectively. If λ₁ = 2λ₂ then the work function of material is given by: (a) K₂ + 2K₁ (b) 2K₂ - K₁ (c) K₁ - 2K₂ (d) K₂ - 2K₁

Answer: (d). K₂ = (hc)/(λ₂) - φ and K₁ = (hc)/(2λ₂) - φ. (hc)/(λ₂) = K₂ + φ ⇒ K₁ = (K₂ + φ)/(2) - φ = (K₂ - φ)/(2) So the answer is (d) φ = K₂ - 2K₁.

K₁ and K₂ be the maximum kinetic energies of photoelectrons emitted… | JEE Main 2026 (8 Apr, Shift 2)

Q28JEE Main 2026 · 8 APR · SHIFT 2Medium

Photoelectric Effect: Einstein's Equation

$K_1$ and $K_2$ be the maximum kinetic energies of photoelectrons emitted from a surface of a given material for the light of wavelength $\lambda_1$ and $\lambda_2$ , respectively. If $\lambda_1 = 2\lambda_2$ then the work function of material is given by:

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Answer: (d)

$K_2 = \frac{hc}{\lambda_2} - \phi$ and $K_1 = \frac{hc}{2\lambda_2} - \phi$ .
$\frac{hc}{\lambda_2} = K_2 + \phi \Rightarrow K_1 = \frac{K_2 + \phi}{2} - \phi = \frac{K_2 - \phi}{2}$
So the answer is (d) $\phi = K_2 - 2K_1$ .

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