2015 AIPMT-I Moving Charges and MagnetismMagnetic Field due to a Circular Coil Easy Question 8 of 15 in Magnetic Field due to a Circular Coil

An electron moving in a circular orbit of radius r makes n rotations per second. The magnetic field produced at the centre has magnitude:

A $\frac{\mu_0 ne}{2\pi r}$
B Zero
C $\frac{\mu_0 n^2e}{r}$
D $\frac{\mu_0 ne}{2r}$

The answer is D.

Solution

Field at the centre of a circular current: $B = \frac{\mu_0 I}{2r}$
Equivalent current: $I = \frac{e}{T} = ne$
$B = \frac{\mu_0 ne}{2r}$

Concept Orbiting charge as current

Magnetic Field due to a Circular Coil in past papers

15 questions from this chapter have appeared across 12 exam years.