Q.
A long magnet is placed vertically with its S -pole resting on the table. A neutral point is obtained 10cm from the pole due geographic north of it. If H=3.2×10−5T, then the pole strength of magnet is
As, the magnet is long, we assume that the upper north pole produces no effect. But due to south pole of the magnet is equal and opposite to horizontal component of earth's magnetic field, i.e., B=(4πμ0)r2m=H
In CGS system, 4πμ0=1 ∴1×102m=3.2×10−5×104 (gauss) m=32ab−amp−cm−1