Question

If a bar magnet of magnetic moment \(M\) is cut into two equal parts perpendicular to its length then its new magnetic moment is

• A. [option in figure]
• B. [option in figure]
• C. [option in figure]
• D. [option in figure]
• E. [option in figure]

Hint:

Cut perpendicular to length: length becomes half, pole strength stays same. So magnetic moment becomes half.

Answer 1

The Correct Option is B

Magnetic moment is: \[ M = m \times 2l \] where \(m\) is pole strength and \(2l\) is magnetic length. If the magnet is cut perpendicular to its length, the length becomes half, but pole strength remains the same. So the new magnetic length becomes: \[ l \] instead of \(2l\). Thus new magnetic moment is: \[ M' = m\times l = \frac{M}{2} \]
Hence, the correct answer is the option corresponding to: \[ \boxed{\frac{M}{2}} \]