Question

The minimum energy that must be given to a $H$ atom in ground state so that it can emit an $H_{\gamma }$ line in Balmer series is, what would be the angular momentum of $H_{\gamma }$ photon if the angular momentum of the system is conserved

• A. $\hslash$
• B. $2\hslash$
• C. $3\hslash$
• D. $4\hslash$

Answer 1

Answer: (C)

According to Bohr's atomic model, angular momentum $L_n=n\hslash$.
If the angular momentum of system is conserved then angular momentum of emitted photon = change in angular momentum of electron corresponding to the transition from $n=5$ to $n=2$ $\therefore L=L_5-L_2$
$=5\hslash -2\hslash =3\hslash$