The force between two charges is 120N. If the distance between the charges is doubed, the force will be:
Correct answer: C. 30N
- A. 60N
- B. 40N
- C. 30N
- D. 15N
Explanation
According to Coulomb's Law: Fe ∝ 1 / r2 {provided the charges remain the same} r1 = r F1 = 120 N r2 = 2r1 = 2r F2 ∝ 1 / (2r)2 ==> F2 ∝ 1 / 4r2 F2 / F1 = (1/4r2) / (1/r2) F2 / F1 = 1/4 F2 = (1 / 4) x 120 = 30N
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Electrostatics describes forces between charges through Coulomb's law, electric fields and field intensity, then uses electric potential to measure energy per unit charge. Capacitors store charge and electrical energy, with capacitance depending on geometry and dielectric material, not simply on the amount of charge present.
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