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AP EAMCET201822 Apr 2018Evening ShiftPhysicsElectrostaticsActual

An electric dipole consists of two particle each of mass 1 ~kg separated by l m carrying charges 1 C and -1 C respectively. It is in equilibrium in a uniform electric field of 2 10^4 Vm ⁻¹ . If it is deflected by a small angle 2^ , minimum time taken by it to come back again to the mean position is (in seconds)

Options

  1. A2.5
  2. B2
  3. C5
  4. D4

Correct answer

A. 2.5

Step-by-step solution

Torque on dipole, when it is deflected by a small angle is =p E =p E for small angle, = But =I where, I=m r^2+m r^2=2 m r^2 So, angular acceleration of dipole is = p E I Time to align back with field is ( . using . = 1 2 t^2 ) t= 2 = 2 I p E = 2 I P E = 50 2 5 ( s )

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