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PhysicsJEE Main 24 Jan 2026, Shift 2·Q8·MCQ·Easy–moderate

Dual Nature of Radiation and Matter · Photoelectric effect

When a light of a given wavelength falls on a metallic surface the stopping potential for photoelectrons is 3.2 V. If a second light having wavelength twice of first light is used, the stopping potential drops to 0.7 V. The wavelength of first light is m.
(h=6.63×10−34h = 6.63\times10^{-34} J.s, e=1.6×10−19e = 1.6\times10^{-19} C, c=3×108c = 3\times10^{8} m/s)
  1. (1)2.9×10−82.9\times10^{-8}
  2. (2)2.2×10−82.2\times10^{-8}
  3. (3)3.1×10−73.1\times10^{-7}
  4. (4)2.5×10−72.5\times10^{-7}

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