Atomic Physics Question 5
Question 5 - 2024 (29 Jan Shift 1)
When a hydrogen atom going from $n=2$ to $n=1$ emits a photon, its recoil speed is $\frac{x}{5} m / s$. Where $x=$ . (Use : mass of hydrogen atom $=1.6 \times 10^{-27} kg$ )
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Answer: (17)
Solution:
$\Delta \mathbf{E}=10.2 eV$
Recoil speed $(v)=\frac{\Delta E}{mc}$
$=\frac{10.2 eV}{1.6 \times 10^{-27} \times 3 \times 10^{8}}$
$=\frac{10.2 \times 1.6 \times 10^{-19}}{1.6 \times 10^{-27} \times 3 \times 10^{8}}$
$v=3.4 m / s=\frac{17}{5} m / s$
Therefore, $x=17$
