Question

Assertion :We cannot think of a magnetic field configuration with three poles Reason: A bar magnet does exert a torque on itself due to its own field.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is D Both Assertion and Reason are incorrect

The bar magnet or any other magnet does not exert a torque on itself in its own magnetic field. Torque $\tau \propto \overrightarrow{M}\times \overrightarrow{B}$. As the magnetic field $\overrightarrow{B}$ is due to the magnetic moment $\overrightarrow{M}$ the value of cross product will be zero. $\because \theta =0$

Magnetic poles exist in pairs. However one can visualize, theoretically, magnetic field due to three poles formed by placing the north poles of the two magnets in contact and the south poles separated by some distance.