Question

When the hydrogen atom emits a photon in going from n = 5 to n= 1 state, its recoil speed is nearly –

• A. 10^–4 m/s
• B. 2 × 10^–2 m/s
• C. 4 m/s
• D. 8 × 10² m/s

Answer 1

Answer: (C)

4 m/s

Answer 2

P = $\frac{E}{c}$ = mv

P = $\frac{13eV}{c}$ = mv

$\frac{13 \times 1.6 \times 10^{–19}}{3 \times 10^{8} \times 1.6 \times 10^{–27}}$ = v