Question

The magnetic moment produced in a sample of 2 gram is \(8\times 10^{-7}\,\text{A/m}^2\). If its density is \(4 \text{g/cm}^3\) then the magnetization of the sample is

• A. \(1.6\)
• B. \(1.2\)
• C. \(1.4\)
• D. \(1.8\)

Hint:

Magnetisation is magnetic moment per unit volume; find the volume from mass and density.

Answer 1

The Correct Option is A

Step 1: Convert units:
Density $4$ g/cm$^3$ $= 4000$ kg/m$^3$ and mass $2$ g $= 0.002$ kg.

Step 2: Volume:
$V = 0.002/4000 = 5\times10^{-7}$ m$^3$.

Step 3: Magnetisation:
$M = 8\times10^{-7}/5\times10^{-7} = 1.6$ A/m, option (A).

Final Answer:
The magnetisation is 1.6 A/m. \[ \boxed{\text{(A) }1.6\ \text{A/m}} \]