Maximum kinetic energy of photoelectrons is ' E ' when wavelength of incident radiation is ' λ '. If wavelength of incident radiations is reduced to (λ)/(3) then maximum kinetic energy of photoelectrons becomes four times. Then work function of the metal is (a) (3hc)/(λ) (b) (hc)/(3λ) (c) (hc)/(λ) (d) (hc)/(2λ)

Answer: (b). E = (hc)/(λ) - φ and 4E = (3hc)/(λ) - φ. (4hc)/(λ) - 4φ = (3hc)/(λ) - φ ⇒ (hc)/(λ) = 3φ So the answer is (b) φ = (hc)/(3λ).

Maximum kinetic energy of photoelectrons is ' E ' when wavelength of… | MHT CET 2023 (10 May, Shift 1)

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Photoelectric Effect: Einstein's Equation

Maximum kinetic energy of photoelectrons is ' $E$ ' when wavelength of incident radiation is ' $\lambda$ '. If wavelength of incident radiations is reduced to $\frac{\lambda}{3}$ then maximum kinetic energy of photoelectrons becomes four times. Then work function of the metal is

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Answer: (b)

$E = \frac{hc}{\lambda} - \phi$ and $4E = \frac{3hc}{\lambda} - \phi$ .
$\frac{4hc}{\lambda} - 4\phi = \frac{3hc}{\lambda} - \phi \Rightarrow \frac{hc}{\lambda} = 3\phi$
So the answer is (b) $\phi = \frac{hc}{3\lambda}$ .

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