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Question: Answered & Verified by Expert
A uniformly charged semicircular arc of radius ' $r$ ' has linear charge density $(\lambda)$. What is the electric field at its centre?
( $\epsilon_0=$ permittivity of free space)
PhysicsElectrostaticsMHT CETMHT CET 2021 (20 Sep Shift 1)
Options:
  • A $\frac{\lambda}{2 \pi \in_0 r}$
  • B $\frac{2 \pi \epsilon_0}{\lambda}$
  • C $\frac{\lambda}{4 \epsilon_0}$
  • D $\frac{2 \epsilon_0}{\lambda}$
Solution:
1449 Upvotes Verified Answer
The correct answer is: $\frac{\lambda}{2 \pi \in_0 r}$
Electric field due to a circular arc at its center,
$\mathrm{E}=\frac{2 \mathrm{k} \lambda}{\mathrm{r}} \sin \alpha$, where $\alpha$ is the angle which arc subtends at its center
For semicircle, $\alpha=90^{\circ}$
Hence, $E=\frac{\lambda}{2 \pi \epsilon_0 r}$

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