MHT CET 2021 Physics Solved Paper

(d) According to Bohr's model, the kinetic energy of moving electron in nth orbit is given as
K=‌

Rhc

n2

‌‌‌⋅⋅⋅⋅⋅⋅⋅(i)
where, R= Rydberg constant, h= Planck's constant and c= speed of light.
Similarly, potential energy of electron moving in nth orbit,
P=−2‌

Rhc

n2

‌‌‌⋅⋅⋅⋅⋅⋅⋅(ii)
From Eqs. (i) and (ii), we have
P=−2K
Total energy of electron moving in nth orbit,
E=K+P=K−2K
E=−K
⇒‌‌K=−E=−(−3.4eV)‌‌(given‌E=−3.4eV)
K = 3.4 eV
From Eq. (iii), we have
P=−2K=−2(3.4)=−6.8eV
∵‌‌P−K=−6.8−3.4=−10.2eV
and K−P=3.4−(−6.8)=10.2eV