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Reviewed CSCA Physics question · Standard

What is the magnitude of the electric field at a distance of 0.5 m from a point charge of 2 x 10^-6 C? (Use k = 9 x 10^9 N m^2/C^2)

  1. 3.6 x 10^4 N/C
  2. 7.2 x 10^4 N/C
  3. 1.8 x 10^5 N/C
  4. 9.0 x 10^9 N/C
Show the answer and explanation

Correct answer

B. 7.2 x 10^4 N/C

Principle or equation

Electric field due to a point charge: E = k Q / r^2.

Why this answer is correct

E = (9 x 10^9)(2 x 10^-6) / (0.5)^2 = (18 x 10^3) / 0.25 = 72 x 10^3 = 7.2 x 10^4 N/C.

Example

For Q = 1 x 10^-6 C at r = 1 m, E = 9 x 10^9 N/C.

This published item includes a stored explanation and passed the platform’s publication workflow. It is independent preparation material, not a claim of an official or recalled examination question.

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