A short bar magnet is placed in the magnetic | vedclass

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(C) For a short bar magnet placed with its north pole pointing towards the geographic north, the neutral points lie on the equatorial line (East-West

Vedclass · Accepted Answer

$9.7$

Vedclass · Answer

(C) For a short bar magnet placed with its north pole pointing towards the geographic north, the neutral points lie on the equatorial line (East-West line).At the neutral point, the magnetic field due to the magnet equals the horizontal component of the Earth's magnetic field $(B_H)$.The formula for the magnetic field on the equatorial line of a short bar magnet is $B = \frac{\mu_0}{4\pi} \cdot \frac{M}{r^3}$.Given: $r = 30 \, cm = 0.3 \, m$, $B_H = 3.6 	imes 10^{-5} \, T$, and $\frac{\mu_0}{4\pi} = 10^{-7} \, T \cdot m/A$.Equating the fields: $10^{-7} \cdot \frac{M}{(0.3)^3} = 3.6 	imes 10^{-5}$.Solving for $M$: $M = \frac{3.6 	imes 10^{-5} 	imes (0.3)^3}{10^{-7}}$.$M = 3.6 	imes 10^2 	imes 0.027$.$M = 360 	imes 0.027 = 9.72 \, A \cdot m^2$.Thus, the magnetic moment is approximately $9.7 \, A \cdot m^2$.

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