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3 point charges each of - q are placed on the circumference of a circle of diameter 2 a at A , B and C respectively as shown in figure. The electric field at O is

Options

  1. AKq a towards OA
  2. BKq 2 a towards OC
  3. CKq a towards OB
  4. DZero

Correct answer

C. Kq a towards OB

Step-by-step solution

The charges are placed at points A, B, and C on the circumference of a circle with center O and radius a . The charges are q_A = -q , q_B = -q , and q_C = -q . The electric field at the center O due to a point charge q at distance a is given by E = Kq a^2 . The electric field at O due to charge at A ( -q ) is E _A = Kq a^2 directed from O towards A (since the charge is negative, the field points towards the charge). The electric field at O due to charge at C ( -q ) is E _C = Kq a^2 directed from O towards C. Since

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