If the two metals A and B are exposed to radiation of wavelength 350 nm. The work functions of metals A and B are 4.8 eV and 2.2 eV. Then choose the correct option. (a) Metal B will not emit photo-electrons (b) Both metals A and B will not emit photo-electrons (c) Metal A will not emit photo-electrons (d) Both metals A and B will emit photo-electrons

Answer: (c). Emission needs photon energy E ≥ φ. E = (1240)/(λ(nm)) eV = (1240)/(350) ≈ 3.54 eV φA = 4.8 eV > E: no emission from A. φB = 2.2 eV < E: B emits. So the answer is (c) Metal A will not emit photo-electrons.

If the two metals A and B are exposed to radiation of wavelength 350… | JEE Main 2023 (31 Jan, Shift 2)

Q73JEE Main 2023 · 31 JAN · SHIFT 2Easy

Photoelectric Effect: Einstein's Equation

If the two metals $\text{A}$ and $\text{B}$ are exposed to radiation of wavelength $350\text{ nm}$ . The work functions of metals $\text{A}$ and $\text{B}$ are $4.8\text{ eV}$ and $2.2\text{ eV}$ . Then choose the correct option.

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Answer: (c)

Emission needs photon energy $E \ge \phi$ .
$E = \frac{1240}{\lambda(\text{nm})}\text{ eV} = \frac{1240}{350} \approx 3.54\text{ eV}$
$\phi_A = 4.8\text{ eV} > E$ : no emission from A. $\phi_B = 2.2\text{ eV} < E$ : B emits.
So the answer is (c) Metal A will not emit photo-electrons.

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