Question

The magnitude of magnetic fields at a distance \( r \) from the centre of a short bar magnet, in longitudinal position to transverse position is in the ratio

• A. 4 : 1
• B. 2 : 1
• C. 1 : 4
• D. 1 : 2

Hint:

In the case of a bar magnet, the magnetic field in the longitudinal position is twice that in the transverse position at the same distance.

Answer 1

The Correct Option is B

Step 1: Understanding the magnetic field of a bar magnet.
For a short bar magnet, the magnetic field at a distance \( r \) from its centre is different in the longitudinal and transverse positions. In the longitudinal position, the field is along the axis of the magnet, and in the transverse position, it is perpendicular to the axis. The ratio of these fields is given by: \[ \frac{B_{\text{long}}}{B_{\text{trans}}} = 2 : 1 \] This is because the field in the longitudinal direction is stronger than in the transverse direction at the same distance from the magnet.
Step 2: Conclusion.
Thus, the correct answer is (B) 2 : 1.