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JEE Main 22-Jan-2025 Paper - Shift 2 — JEE STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceJEEJEE Main 22-Jan-2025 Paper - Shift 24 Marks
MCQ
A light source of wavelength $\lambda$ illuminates a metal surface and electrons are ejected with maximum kinetic energy of 2 eV . If the same surface is illuminated by a light source of wavelength $\frac{\lambda}{2}$, then the maximum kinetic energy of ejected electrons will be (The work function of metal is 1 eV )
  • A
    2 eV
  • B
    6 eV
  • ✓
    5 eV
  • D
    3 eV
✓

Answer

Correct option: C.
5 eV
(C) 5 eV
Sol. $\frac{ hc }{\lambda}=\phi+ eV \Rightarrow \frac{ hc }{\lambda}=1+2=3 eV$ ......(1)
$\frac{ hc }{\lambda / 2}=6=1+ k _{\max } \quad \therefore k _{\max }=5 eV$

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