Question

A solenoid has core of a material with relative permeability 200 and its windings carry a current of 2 A. The number of turns of the solenoid is 200 per meter. What is the magnetization of the material?

(a) 6 × 10^4 A/m

(b) 7 × 10^4 A/m

(c) 8 × 10^4 A/m

(d) 9 × 10^4 A/m

The question was posed to me in an interview for internship.

This interesting question is from Solenoid and Toroid in chapter Moving Charges and Magnetism of Physics – Class 12

Answer 1

The correct answer is (c) 8 × 10^4 A/m

The explanation: Given: number of turns (n) = 200 turns per meter; current (I) = 2 A; Relative permeability (µr) = 200

Magnetic intensity is given by: H = nI = 200 × 2 = 400 A/m

μr = 1 + γ → γ is the magnetic susceptibility of the material

γ = μr – 1

Magnetization → M = γ x H

M = (μr – 1) × H

M = (200 – 1) × 200

M = 199 × 200

M = 79600

M = 7.96 × 10^4  A/m ≈ 8 × 10^4 A/m