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JEE Main 2022 (27 Jun, Shift 2) · Electric Charge & Coulomb's Law

Electric Charge & Coulomb's Law question from JEE Main 2022 (27 Jun, Shift 2)

Q49JEE Main 2022 · 27 JUN · SHIFT 2Difficult

Electric Charge & Coulomb's Law

Three identical charged balls each of charge 2 C are suspended from a common point P by silk threads of 2 m each (as shown in figure). They form an equilateral triangle of side 1m. The ratio of net force on a charged ball to the force between any two charged balls will be:

Figure

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Answer: (d)

  1. Force between any two balls: F=kq2(1)2F = \dfrac{kq^2}{(1)^2}.
  2. On one ball, the other two balls exert two forces of magnitude FF with 60∘60^\circ between them.
  3. Net electric force =F2+F2+2F2cos⁡60∘=3F= \sqrt{F^2 + F^2 + 2F^2\cos 60^\circ} = \sqrt{3}F
  4. Ratio =3F:F=3:1= \sqrt{3}F : F = \sqrt{3} : 1
  5. So the answer is (d) 3:1\sqrt{3} : 1.
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