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JEE Main202126 Feb 2021Morning ShiftPhysicsElectrostaticsActual

Find the electric field at point P (as shown in figure) on the perpendicular bisector of a uniformly charged thin wire of length L carrying a charge Q . The distance of the point P from the centre of the rod is a = 3 2 L

Options

  1. AQ 3 π ε 0 L 2
  2. BQ 2 3 π ε 0 L 2
  3. C3 Q 4 π ε 0 L 2
  4. DQ 4 π ε 0 L 2

Correct answer

B. Q 2 3 π ε 0 L 2

Step-by-step solution

E = k λ a sin θ 1 + sin θ 2 E = 1 4 π ε 0 × Q L × 1 3   L 2 × 2 sin θ tan θ = L / 2 3   L 2 = 1 3 sin θ = 1 2 E = 1 4 π ε 0 × 2 Q 3   L 2 × 2 × 1 2 E = Q 2 3 π ε 0   L 2

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