Question

If the velocity of the revolving electron of $He ^{+}$ in the first orbit $( n =1$ ) is $v$, the velocity of the electron in the second orbit is :

• A. v
• B. 0.5 v
• C. 2 v
• D. 0.25 v

Answer 1

Answer: (B)

For single electron species $v_{n} \propto \frac{1}{n}$
$\frac{v_{2}}{v_{1}}=\frac{ n _{1}}{ n _{2}}=\frac{1}{2}$
$v_{2}=\frac{1}{2} v_{1}=\frac{1}{2} v=\frac{v}{2}=0.5\, v$