Question

The angular momentum of an electron in a given orbit is J, Its kinetic energy will be :

• A. $\frac{1}{2}\frac{J^{2}}{mr^{2}}$
• B. $\frac{Jv}{r}$
• C. $\frac{J^{2}}{2m}$
• D. $\frac{J^{2}}{2\pi}$

Answer 1

Answer: (A)

$\frac{1}{2}\frac{J^{2}}{mr^{2}}$

Answer 2

Angular momentum J = mvr

J2 = m2v2r2

or $\frac{J^{2}}{2} = \left( \frac{1}{2}mv^{2} \right)mr^{2} or K.E. = \frac{J^{2}}{2mr^{2}}$