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JEE Main 2024 (6 Apr, Shift 2) · Electric Charge & Coulomb's Law

Electric Charge & Coulomb's Law question from JEE Main 2024 (6 Apr, Shift 2)

Q31JEE Main 2024 · 6 APR · SHIFT 2Medium

Electric Charge & Coulomb's Law

Two identical conducting spheres P and S with charge Q on each, repel each other with a force 16 N16\text{ N}. A third identical uncharged conducting sphere RR is successively brought in contact with the two spheres. The new force of repulsion between PP and SS is:

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Answer: (b)

  1. R touches P: P=Q2P = \dfrac{Q}{2}, R=Q2R = \dfrac{Q}{2}. R touches S: S=Q/2+Q2=3Q4S = \dfrac{Q/2 + Q}{2} = \dfrac{3Q}{4}.
  2. F′=k(Q/2)(3Q/4)r2=38FF' = \dfrac{k(Q/2)(3Q/4)}{r^2} = \dfrac{3}{8}F
  3. F′=38×16=6 NF' = \dfrac{3}{8} \times 16 = 6\text{ N}. So the answer is (b) 6 N.
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