Q130 / 200 · NEET 2007 · Physics

A charged particle (charge $q$) is moving in a circle of radius $R$ with uniform speed $v$. The associated magnetic moment $\mu$ is given by:

  • A
    $q v R^2$
  • B
    $q v R^2 / 2$
  • C
    $q v R$
  • Correct answer
    D
    $q v R / 2$.

Solution

Magnetic moment $\mu=I A$ Since $T=\frac{2 \pi R}{v}$ also $I=\frac{q}{T}=\frac{q v}{2 \pi R}$ $\begin{aligned} \therefore \quad \mu & =\left(\frac{q v}{2 \pi R}\right)\left(\pi R^2\right) \\ & =\frac{q v R}{2} \end{aligned}$

Hence, the correct answer is option: 'D'.

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