Question

The kinetic energy of the electron in an orbit of radius ${}^{\prime }{r}^{\prime }$ in hydrogen atom is ($e=$electronic charge)

• A. $\frac{e^2}{r^2}$
• B. $\frac{e^2}{2r}$
• C. $\frac{e^2}{r}$
• D. $\frac{e^2}{2r^2}$

Answer 1

The correct option is B $\frac{e^2}{2r}$

Potential energy of electron in $n^{th}$ orbit of radius $r$ in H-atom, $U=-\frac{e^2}{r}$(in CGS)

$\because K.E.=\frac{1}{2}|P.E.|\Rightarrow K=\frac{e^2}{2r}$