An electron moves in Bohr's orbit. The magnetic field at the centre is proportional to

Options

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

Answer

A

Explanation

`B=(mu_(0)I)/(2 a)`
`B=(mu_(0)qF)/(2a)`
`B prop F/a` but `F prop 1/n^(3)` and `a prop n^(2)`
`:. B prop 1/n^(5)`
`B prop n^(-5)`.