NCERT Class XII Chapter
Magnetism and Matter
Questions With Solutions
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Question : 13
Total: 25
A short bar magnet placed in a horizontal plane has its axis aligned along the magnetic north-south direction. Null points are found on the axis of the magnet at 14 cm from the centre of the magnet. The earth’s magnetic field at the place is 0.36 G and the angle of dip is zero. What is the total magnetic field on the normal bisector of the magnet at the same distance as the null-point (i.e., 14 cm) from the centre of the magnet? (At null points, field due to a magnet is equal and opposite to the horizontal component of earth’s magnetic field.)
Solution:
Angle of dip is zero at the place, so earth’s magnetic field is uniform with magnitude 0.36 G in the direction geographical south to geographical north.
At axial position for null point
At equatorial position the field due to bar magnet is
Total magnetic field of earth and magnet adds at equatorial position
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