Question

A toroidal solenoid has 3000 turns and a mean radius of 10cm. It has a soft iron core of relative permeability 2000. Find the magnetic field in the core when a current of 1.0A is passed through the solenoid.

• A. 20T
• B. 12T
• C. 6T
• D. 3T

Answer 1

Answer: (B)

12T

Answer 2

$B=\frac{\mu N i}{2\pi\,r}$