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← JEE Main 2022 · 30 Jul · Shift 2
PhysicsSingle correct+4 / -1Question 10 of 90

JEE Main 2022 · 30 Jul · Shift 2, Physics question 10

A charge q is uniformly distributed along the length L of a rod. It is then bent in the shape of a semicircle. The magnitude of electric field at the centre of semicircle will be :

Choose one option
Answer and worked solution

Official answer: A

Semicircle of radius R=LπR=\frac L\pi with λ=qL\lambda=\frac qL: E=2kλR=24πϵ0⋅qL⋅πL=q2ϵ0L2E=\dfrac{2k\lambda}R=\dfrac{2}{4\pi\epsilon_0}\cdot\dfrac qL\cdot\dfrac\pi L=\dfrac q{2\epsilon_0L^2}.

(A)