λ = hc/φ = (6.63×10⁻³⁴ × 3×10⁸)/(4.2 × 1.6×10⁻¹⁹) ≈ 296 nm
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JEE Main 2026 — Physics Modern Physics
medium
mcq
2026
Official previous-year question
Verified 30 May 2026.
Question
The work function of a metal is 4.2 eV. The threshold wavelength for photoelectric emission is approximately:
Options
- A
196 nm
- B
296 nm
- C
396 nm
- D
496 nm
Solution
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