Question

A solenoid having \(400\text{ turns/metre}\) has a core of a material with relative permeability \(300\). If a current of \(0.5\text{ A}\) is passed through it, then the magnetisation of the core material is nearly

• A. \(6 \times 10^2\text{ A/m}\)
• B. \(6 \times 10^3\text{ A/m}\)
• C. \(6 \times 10^4\text{ A/m}\)
• D. \(6 \times 10^5\text{ A/m}\)

Hint:

Formula: $M = (\mu_r - 1)nI$

Answer 1

The Correct Option is C

Concept: \[ H = nI \quad , \quad M = (\mu_r - 1)H \]

Step 1: Calculate $H$. \[ H = 400 \times 0.5 = 200 \text{ A/m} \]

Step 2: Magnetisation. \[ M = (300 - 1)\times 200 \approx 299 \times 200 = 59800 \approx 6 \times 10^4 \]

Step 3: Conclusion.
$M \approx 6 \times 10^4 \text{ A/m}$ Final Answer: Option (C)