A bar magnet has length \(3\text{ cm}\), cross-sectional area \(2\text{ cm}^2\) and magnetic moment \(3\text{ A m}^2\). The intensity of magnetisation of bar magnet is
\(2 \times 10^5\text{ A/m}\)
\(3 \times 10^5\text{ A/m}\)
\(4 \times 10^5\text{ A/m}\)
\(5 \times 10^5\text{ A/m}\)
Solution:
Intensity of magnetisation \(I = \frac{M}{V}\). Here, volume \(V = A \times L = (2 \times 10^{-4}\text{ m}^2) \times (3 \times 10^{-2}\text{ m}) = 6 \times 10^{-6}\text{ m}^3\). Thus, \(I = \frac{3}{6 \times 10^{-6}} = 5 \times 10^5\text{ A/m}\).
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