Question

When an electron of H-atom jumps from a higher to lower energy state, then:

a) Its potential energy decreases

b) Its kinetic energy increases

c) Its angular momentum remains unchanged

d) Wavelength of de Broglie wave associated with the electron
decreases

Solution

As e^- moves from higher orbit:

As decreases E_n, kinetic energy increases.

Because K.E = -E_n

Similarly, P.E = 2E_n

Potential energy decreases.

Angular momentum (L)= (nh)/(2pi)=> L  decreases as n decreases.

lambda_c = h/(mv_n)

Since K.E increases, v_n increases. Therefore, lambda_c decreases.

Therefore, option (a),(b) and (d) are correct.