According to Bohr's theory, the time averaged magnetic field at the centre (i.e. nucleus) of a hydrogen atom due to the motion of electrons in the `n^(th)` orbit is proportional to :
(n = principal quantum number)

Options

A. `n^(-4)`
B. `n^(-5)`
C. `n^(-3)`
D. `n^(-2)`

Answer

A

Explanation

The magnetic field at the centre of Hydrogen nucleus can be calculated as :
`B=(mu_0I)/(2r)` …(i)
The current `I=(ev)/(2pir)`
`B=(ev)/(4pir^2)`
According to Bohr.s model , radius of `n^(th)` orbit `r prop n^2` From equation (i) it can be concluded : `B prop n^(-4)`