The linear charge density on a dielectric ring of radius $R$ varies with $\theta $ as $\lambda \, = \,{\lambda _0}\,\cos \,\,\theta /2,$ where $\lambda _0$ is constant. Find the potential at the centre $O$ of ring. [in volt]
$\lambda _0\,\,R$
$\frac {\lambda _0\,R}{2}$
$\frac {\lambda _0}{4\pi \epsilon _0R }$
zero
Which of the following statements is true about the flow of electrons in an electric circuit?
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