Q 12-05-006NEETEAMCET 2007 (Medical)Medium
A bar magnet of magnetic moment $M_1$ is axially cut into two equal parts. If these two pieces are arranged perpendicular to each other, the resultant magnetic moment is $M_2$. Then the value of $\dfrac{M_1}{M_2}$ is
Answer: (D) $\sqrt{2}$
Cutting along the axis halves the pole strength and keeps the length, so each piece has moment $\dfrac{M_1}{2}$.
At right angles: $M_2 = \sqrt{2}\cdot\dfrac{M_1}{2} = \dfrac{M_1}{\sqrt{2}}$, so $\dfrac{M_1}{M_2} = \sqrt{2}$.
Solution by Sreeraj P, M.Sc Physics