JEE PYQ: Atomic Physics Question 22
Question 22 - 2021 (26 Feb Shift 2)
The recoil speed of a hydrogen atom after it emits a photon in going from $n = 5$ state to $n = 1$ state will be:
(1) 4.17 m/s
(2) 4.34 m/s
(3) 219 m/s
(4) 3.25 m/s
Show Answer
Answer: (1)
Solution
Momentum $P = \frac{\Delta E}{c} = \frac{(13.6 - 0.54) \text{eV}}{3 \times 10^8}$. $mv = \frac{(13.06) \times 1.6 \times 10^{-19}}{3 \times 10^8}$. $v = \frac{(13.06) \times 1.6 \times 10^{-19}}{3 \times 10^8 \times 1.67 \times 10^{-27}} \approx 4.17$ m/s.
BETA
