Question

A bar magnet $AB$ is cut into two equal parts (as shown in figure). One part is kept over the other such that the pole $C_2$ is above $C_1$. If $M$ is the magnetic moment of the original magnet, the magnetic moment of the combination so formed is

• A. $M$
• B. $\dfrac{M}{2}$
• C. Zero
• D. $2M$

Hint:

Magnetic moments cancel when equal magnets are placed with opposite orientations.

Answer 1

The Correct Option is C

Step 1: Effect of cutting the magnet.
When a bar magnet is cut into two equal parts, each part has magnetic moment $\dfrac{M}{2}$.

Step 2: Orientation of the two parts.
The two pieces are arranged one above the other with opposite poles aligned vertically.
Thus, their magnetic moments are equal in magnitude but opposite in direction.

Step 3: Resultant magnetic moment.
\[ M_{\text{net}} = \frac{M}{2} - \frac{M}{2} = 0 \]

Step 4: Conclusion.
The magnetic moment of the combination is zero.