Permanent magnetismMedium
Question
An iron bar of length $L$ has magnetic moment $M$. It is bent at the middle of its length such that the two arms make an angle $60^{\circ}$ with each other. The magnetic moment of this new magnet is :
Options
A.$2M$
B.$\frac{M}{\sqrt{3}}$
C.$M$
D.$\frac{M}{2}$
Solution
Sol. [Key Concept: Magnetic moment of a bent bar magnet]
$M = ml$.
$$\begin{matrix} \Delta l & \ = 2\frac{l}{2}sin30^{\circ} \\ & \ = \frac{l}{2} \\ M^{'} & \ = ml/2 \\ & \ = M/2 \end{matrix}$$
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