Q73 / 90 · JEE Main 2015 (04 Apr) · Physics

As an electron makes a transition from an excited state to the ground state of a hydrogen-like atom/ion

A
kinetic energy and total energy decrease but potential energy increases
Correct answer
B
its kinetic energy increases but potential energy and total energy decrease
C
kinetic energy, potential energy and total energy decrease
D
kinetic energy decreases, potential energy increases but total energy remains same

Solution

U = - \frac{e^{2}}{4 {πε}_{0} r}

U

=

potential energy,

K = \frac{e^{2}}{4 {πε}_{0} r}

K

=kinetic energy.

E = U + K = - \frac{e^{2}}{8 {πε}_{0} r}

E

=total energy

∴

As electron de-excites from an excited state to ground state,

K

increases, but

U

and

E

decrease.

Hence, the correct answer is option: 'B'.