Atomic structure problem - 10th Feb'16

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.