JEE Main 2022 · 25 Jul · Shift 1 · Physics Q47

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A metal exposed to light of wavelength 800 nm and and emits photoelectrons with a certain kinetic energy. The maximum kinetic energy of photo-electron doubles when light of wavelength 500 nm is used. The workfunction of the metal is : (Take hc = 1230 eV-nm).

1.537 eV

2.46 eV

0.615 eV

1.23 eV

Answer and worked solution

Official answer: C

Einstein. $2\left(\frac{1230}{800}-\phi\right)=\frac{1230}{500}-\phi$ , so $\phi=3.075-2.46=0.615$ eV.

(C)

Topics:Photoelectric effect

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JEE Main 2022 · 25 Jul · Shift 1, Physics question 47