Question
As an electron makes a transition from an excited state to the ground state of a hydrogen - like atom/ion :
A.
kinetic energy decreases, potential energy increases but total energy remains same
B.
kinetic energy and total energy decrease but potential energy increases
C.
its kinetic energy increases but potential energy and total energy decrease
D.
kinetic energy, potential energy and total energy decrease
Answer :
its kinetic energy increases but potential energy and total energy decrease
Solution :
$$\eqalign{
& U = - K\frac{{z{e^2}}}{r};T.E = - \frac{k}{2}\frac{{z{e^2}}}{r} \cr
& K.E = \frac{k}{2}\frac{{z{e^2}}}{r}.\,{\text{Here}}\,r\,{\text{decreases}} \cr} $$