NTA Abhyas JEE Main2020PhysicsAtomic PhysicsPractice
Imagine an electron moving in the potential field of a proton given by V = V 0  ln r r 0 where r 0 is a positive constant and r is the distance between the electron and proton. Assuming Bohr's model to be applicable, the variation of r n with n (principal quantum number) is
Options
- Ar n ∝ n
- Br n ∝ 1 n
- Cr n ∝ n 2
- Dr n ∝ 1 n 2
Correct answer
A. r n ∝ n
Step-by-step solution
U = eV = eV 0 ln r r 0 F = - dU dr = eV 0 r This force provide the necessary centripetal force. Hence mv 2 r = eV 0 r or v = eV 0 m ...(1) Moreover, mvr = nh 2 π ...(2) Dividing Eq. (2) by Eq. (1), we have mr = nh 2 π m eV 0 or r n ∝ n