Electric Charge & Coulomb’s Law — A/L Physics

How do I practise Electric Charge & Coulomb’s Law?

1 question with a worked solution

1. Two point charges +q and +4q are held fixed at a distance r apart in vacuum, repelling each other with an electrostatic force F. If the distance between them is doubled to 2r, what is the new electrostatic force between them?
   1. A) F / 4
   2. B) 2F
   3. C) 4F
   4. D) F / 2
   Check my answer

   Correct answer: A) F / 4

   According to Coulomb's Law, the electrostatic force between two point charges is inversely proportional to the square of their separation distance: F ∝ 1 / r². When the separation r becomes 2r, F' ∝ 1 / (2r)² = 1 / (4r²) = F / 4.

   Show worked solution

   Step 1: Coulomb's Law: F = (1 / 4πε₀) · (q₁ q₂ / r²). Step 2: When r' = 2r, F' = F / (2)² = F / 4. Answer: F / 4.
   Modelled on: the A/L Physics examination pattern

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Where does Electric Charge & Coulomb’s Law fit in the syllabus?

Unit 6.1 · Year 1 · Term 3