A short bar magnet has a length 2 l and a magnetic moment 10 A m 2 . Find the magnetic field at a distance of z = 0 . 1 m from its centre on the axial line. Here, l is negligible as compared to z .

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TestHub · Accepted Answer

If the point lies on the axial line of bar magnet

$B = \frac{μ . 2 M d}{4 π {(d^{2} - l^{2})}^{2}}$

If $l < < d$ (as given in the question)

$B = \frac{μ_{0}}{4 π} \times \frac{2 M}{d^{3}}$

$= \frac{μ_{0}}{4 π} \times 20 \times 10^{3}$

$(\frac{μ_{0}}{4 π} = 10^{- 7})$

$= 2 \times 10^{- 3} T$

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