The solenoid has a core with a material of relative permeability of 500. The windings of the solenoid are insulated from the core and carry a current of 1A. If the number of turns is 500 per meter, then magnetisation is?

a) 2.5 x 10³ A/m

b) 2.5 x 10⁵ A/m

c) 2.0 x 10³ A/m

d) 2.0 x 10³ A/m

Answer: b) 2.5 x 10⁵ A/m

Solution:

Here, n = 500 turns/m

I = 1 A

μ_r = 500

Magnetic intensity, H = nI = 500 x 1= 500 A/m

μ_r = 1 + χ

Where χ is the magnetic susceptibility of the material

χ =  μ_r – 1

Magnetisation M =χH

=  (μ_r – 1)H

= (500 – 1) x 500

= 499 x 500

= 2.495 x 10⁵ A/m

= 2.5 x 10⁵ A/m