Q. A solenoid has core of a material with relative permeability 500 and its windings carry a current of $1A$. The number of turns of the solenoid is 500 per metre. The magnetization of the material is nearly
A) $2.5 \times 10^{3}\ Am^{- 1}$
B) $2.5 \times 10^{5}\ Am^{- 1}$
C) $2.0 \times 10^{3}\ Am^{- 1}$
D) $2.0 \times 10^{5}\ Am^{- 1}$
Explanation
(b) Here, $n = 500$ turns/m, $I = 1A,\ \mu_{r} = 500$
Magnetic intensity, $H = nI = 500m^{- 1} \times 1A = 500Am^{- 1}$
As $\mu_{r} = 1 + \chi$, where $\chi$ is the magnetic susceptibility of the material
or $\chi = (\mu_{r} - 1)$
Magnetisation, $M = \chi H = (\mu_{r} - 1)H$
$= (500 - 1) \times 500Am^{- 1} = 499 \times 500Am^{- 1}$
$= 2.495 \times 10^{5}\ Am^{- 1}$
$= 2.5 \times 10^{5}\ Am^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.