Light of wavelength ' λ ' falls on a metal having work function (hc)/(λ₀). Photoelectric effect will take place only if ( λ₀ is the threshold wavelength) (a) λ ≥ λ₀ (b) λ ≥ 2λ₀ (c) λ ≤ λ₀ (d) λ = 4λ₀

Answer: (c). Emission needs photon energy ≥ work function: (hc)/(λ) ≥ (hc)/(λ₀) This gives λ ≤ λ₀ So the answer is (c) λ ≤ λ₀.

Light of wavelength ' λ ' falls on a metal having work function… | MHT CET 2025 (20 Apr, Shift 1)

Q31MHT CET 2025 · 20 APR · SHIFT 1Easy

Photoelectric Effect: Einstein's Equation

Light of wavelength ' $\lambda$ ' falls on a metal having work function $\frac{hc}{\lambda_0}$ . Photoelectric effect will take place only if ( $\lambda_0$ is the threshold wavelength)

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Answer: (c)

Emission needs photon energy $\ge$ work function: $\dfrac{hc}{\lambda} \ge \dfrac{hc}{\lambda_0}$
This gives $\lambda \le \lambda_0$
So the answer is (c) $\lambda \le \lambda_0$ .

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