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MHT CET Medical202621 April 2026Evening ShiftPhysicsElectrostaticsActual

Four point charges -Q , -q , 2q and 3Q are placed at corners of the square respectively. The relation between Q and q for which the potential at the centre of the square is zero, is

Options

  1. AQ = q
  2. BQ = -q/2
  3. CQ = -1/q
  4. DQ = 1/2q

Correct answer

B. Q = -q/2

Step-by-step solution

Let the side length of the square be a . The distance of the centre from each corner is r = a 2 . The electric potential at the centre of the square is the algebraic sum of the potentials due to all four charges. V = 1 4 ₀ ( -Q r + -q r + 2q r + 3Q r ) Given that V = 0 , we have: -Q - q + 2q + 3Q = 0 2Q + q = 0 Q = - q 2 Answer: Q = -q/2

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