Radiation emitted by the hydrogen transition n=2 to n=1 irradiates a photosensitive material. The stopping potential is 3.57 V. If the threshold frequency is x × 10¹⁴ Hz, find x.
Physics · Atomic Structure and X-rays
JEE Mains Advanced

Question

Radiation emitted by the hydrogen transition n=2 to n=1 irradiates a photosensitive material. The stopping potential is 3.57 V. If the threshold frequency is x × 10¹⁴ Hz, find x.

G1 Physics · Accepted Answer

The H 2→1 photon energy is 10.2 eV. Einstein's equation gives φ = 10.2−3.57 = 6.63 eV. Then ν₀=φ/h ≈ 16×10¹⁴ Hz, so x=16.