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JEE Main 2022 (28 Jun, Shift 1) · Electric Field & Field Lines

Electric Field & Field Lines question from JEE Main 2022 (28 Jun, Shift 1)

Q25JEE Main 2022 · 28 JUN · SHIFT 1Medium

Electric Field & Field Lines

The three charges q/2, q and q/2 are placed at the corners A, B and C of a square of side 'a' as shown in figure. The magnitude of electric field (E) at the corner D of the square, is:

Figure

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Answer: (a)

  1. Let E0=q4πε0a2E_0 = \dfrac{q}{4\pi\varepsilon_0 a^2}. AA and CC (q/2q/2 each, distance aa) give E02\dfrac{E_0}{2} each, at right angles.
  2. Their resultant along diagonal BDBD: 2⋅E02=E02\sqrt{2}\cdot\dfrac{E_0}{2} = \dfrac{E_0}{\sqrt{2}}
  3. BB (qq, distance 2a\sqrt{2}a) gives E02\dfrac{E_0}{2}, also along BDBD away from BB.
  4. E=E0(12+12)E = E_0\left(\dfrac{1}{\sqrt{2}} + \dfrac{1}{2}\right)
  5. So the answer is (a).
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