A ray of light with wavelength λ is incident on three different photoelectric cells namely 1,2 and 3. The threshold wavelength of these photoelectric cells are λ₁, λ₂, and λ₃, respectively and the magnitude of stopping potentials of these cells are V₁, V₂ and V₃, respectively. The relation between λ and threshold wavelengths are λ₁ λ and λ₃ λ. The correct option is: (a) V₁ V₃ (d) V₁ > V₂, V₃ = 0

Answer: (b). Cell 1: λ > λ₁, photon energy below work function, no emission, so V₁ = 0. eV = (hc)/(λ) - (hc)/(λ₀): larger threshold λ₀ means smaller work function and larger V. λ₃ λ₂, so V₃ > V₂. So the answer is (b) V₁ = 0, V₂ < V₃.

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Photoelectric Effect: Einstein's Equation

A ray of light with wavelength $\lambda$ is incident on three different photoelectric cells namely 1,2 and 3. The threshold wavelength of these photoelectric cells are $\lambda_1, \lambda_2$ , and $\lambda_3$ , respectively and the magnitude of stopping potentials of these cells are $V_1, V_2$ and $V_3$ , respectively. The relation between $\lambda$ and threshold wavelengths are $\lambda_1 < \lambda, \lambda_2 > \lambda$ and $\lambda_3 \gg \lambda$ . The correct option is:

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Answer: (b)

Cell 1: $\lambda > \lambda_1$ , photon energy below work function, no emission, so $V_1 = 0$ .
$eV = \dfrac{hc}{\lambda} - \dfrac{hc}{\lambda_0}$ : larger threshold $\lambda_0$ means smaller work function and larger $V$ .
$\lambda_3 \gg \lambda_2$ , so $V_3 > V_2$ .
So the answer is (b) $V_1 = 0,\ V_2 < V_3$ .

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