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The electric potential at a point due to a point charge at a distance of 45 cm is -40 V . The value of the point charge is: (Assume 1 4 ₀ = 9 10^9 N m ^2 C ⁻² )

Options

  1. A-200 nC
  2. B+2 nC
  3. C-2 nC
  4. D-0.9 nC

Correct answer

C. -2 nC

Step-by-step solution

The electric potential due to a point charge is given by V = 1 4 ₀ Q r Given data: V = -40 V r = 45 cm = 0.45 m Rearranging the formula to solve for the charge Q : Q = V r 1 4 ₀ Substituting the values: Q = -40 0.45 9 10^9 Q = -18 9 10^9 Q = -2 10⁻⁹ C Q = -2 nC Answer: -2 nC

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