Question

A 90.0 A current circulates around a 2.40-mm-diameter superconducting ring. What is the ring's magnetic dipole moment? What is the on-axis magnetic field strength 4.90 cm from the ring?

Answer 1

Given, current, I = 90.0 A

Diameter = 2.40 mm

Radius,r = 1.20 mm = 1.2 * 10^-3 m

Area of the ring, A =

=   m²

⁼

Magnetic dipole moment = I * Area = 90 * 4.52*10^-6 A.m²

= 407 * 10^-6 A.m²

= 4.07 *10^-4 A.m²

Calculation of on axis magnetic field

The formula of on-axis magnetic field is given by

Where x is the distance of the point from the ring. Here, x= 4.90 cm = 4.90 *10^-2 m

We know that , and putting values of I and r in the above equation, we can calculate B.

B= 6.9*10^-7 Tesla