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Two particles A and B having charges 20 μ C and - 5 μ C respectively are held fixed with a separation of 5 cm At what position a third charged particle should be placed so that it does not experience a net electric force ?

Options

  1. AAt 5   cm from - 5   μ C on the right side
  2. BAt 5   cm from 20   μ C on the left side of system
  3. CAt 1 . 25   cm from - 5   μ C between two charges
  4. DAt midpoint between two charges

Correct answer

A. At 5   cm from - 5   μ C on the right side

Step-by-step solution

Charge should be placed near - 5 μ C at x distance K ( 20 ) Q ( 5 + x ) 2 = K ( 5 ) Q X 2 4 x 2 = ( 5 + x ) 2 4 x 2 = 25 + x 2 + 10 x 3 x 2 - 10 x - 25 = 0 ⇒ x = 5

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