Monochromatic radiation emitted when a hydrogen electron falls from first excited to ground state illuminates material of stopping potential 3.57 V. Threshold frequency is closest to:
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Monochromatic radiation emitted when a hydrogen electron falls from first excited to ground state illuminates material of stopping potential 3.57 V. Threshold frequency is closest to:

G1 Physics · Accepted Answer

The 2→1 photon has energy 10.2 eV. Work function W = 10.2 − 3.57 = 6.63 eV. Threshold frequency ν₀ = W/h = (6.63 × 1.602 × 10⁻¹⁹)/(6.626 × 10⁻³⁴) ≈ 1.60 × 10¹⁵ Hz. Answer: C.