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Two charges 7 c and -4 c are placed at (-7 ~cm , 0,0) and (7 ~cm , 0,0) respectively. Given, ₀=8.85 10⁻¹² C ^2 ~N ⁻¹ ~m ⁻² , the electrostatic potential energy of the charge configuration is :

Options

  1. A-1.8 J
  2. B-2.0 J
  3. C-1.5 J
  4. D-1.2 J

Correct answer

A. -1.8 J

Step-by-step solution

P.E. of two charges aligned & u = 1 4 ₀ q ₁ q ₂ r & r = ( x ₂- x ₁ )^2+ ( y ₂- y ₁ )^2+ ( z ₂- z ₁ )^2 & =14 ~cm & u = 9 10^9 7 10⁻⁶ (-4) 10⁻⁶ 14 10⁻² & =-1.8 ~J aligned

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