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Two small spherical balls of mass 10 g each with charges -2 C and 2 C , are attached to two ends of very light rigid rod of length 20 cm. The arrangement is now placed near an infinite nonconducting charge sheet with uniform charge density of 100 C / m ^2 such that length of rod makes an angle of 30^ with electric field generated by charge sheet. Net torque acting on the rod is: (Take ₀: 8.85 10⁻¹² C ^2 / Nm ^2 )

Options

  1. A112 Nm
  2. B1.12 Nm
  3. C2.24 Nm
  4. D11.2 Nm

Correct answer

B. 1.12 Nm

Step-by-step solution

aligned E & = 2 ₀ & = PE aligned aligned & = [ (2 10⁻⁶ ) ( 2 10 ) ] [ 100 10⁻⁶ 2 8.85 10⁻¹² ] ( 1 2 ) & = 10 8.85 =1.12 Nm aligned

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