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JEE Main 2022 (28 Jun, Shift 2) · Electric Field & Field Lines

Electric Field & Field Lines question from JEE Main 2022 (28 Jun, Shift 2)

Q23JEE Main 2022 · 28 JUN · SHIFT 2Easy

Electric Field & Field Lines

Two point charges A and B of magnitude +8 ×\times 10−-6 C and −-8 ×\times 10−-6 C respectively are placed at a distance d apart. The electric field at the middle point O between the charges is 6.4 ×\times 104 NC−1{}^{-1}. The distance 'd' between the point charges A and B is:

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Answer: (b)

  1. At the midpoint the fields of +q+q and −q-q both point towards BB, so they add.
  2. E=2kq(d/2)2=8kqd2E = 2\dfrac{kq}{(d/2)^2} = \dfrac{8kq}{d^2}
  3. 6.4×104=8×9×109×8×10−6d2=5.76×105d26.4 \times 10^4 = \dfrac{8 \times 9 \times 10^9 \times 8 \times 10^{-6}}{d^2} = \dfrac{5.76 \times 10^5}{d^2}
  4. d2=9⇒d=3 md^2 = 9 \Rightarrow d = 3\text{ m}
  5. So the answer is (b) 3.0 m.
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