Atomic Physics Question 7
Question 7 - 2024 (29 Jan Shift 2)
Hydrogen atom is bombarded with electrons accelerated through a potential different of V, which causes excitation of hydrogen atoms. If the experiment is being formed at $T=0 K$. The minimum potential difference needed to observe any Balmer series lines in the emission spectra will be $\frac{\alpha}{10} V$, where $\alpha=$
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Answer: (121)
Solution:
For minimum potential difference electron has to make transition from $n=3$ to $n=2$ state but first electron has to reach to $n=3$ state from ground state. So, energy of bombarding electron should be equal to energy difference of $n=3$ and $n=1$ state.
$\Delta E=13.6\left[1-\frac{1}{3^{2}}\right] e=eV$
$\frac{13.6 \times 8}{9}=V$
$V=12.09 V \approx 12.1 V$
So, $\alpha=121$
