A parallel plate capacitor with plate area A and separation d has a charge Q. The force between the plates is:
Correct answer: A. Q²/(2ε₀A)
- A. Q²/(2ε₀A)
- B. Q²/(ε₀A)
- C. Q²/(4πε₀d²)
- D. Zero
Explanation
The force between capacitor plates is F = Q²/(2ε₀A), derived from the energy stored U = Q²/(2C) and F = -dU/dd, where C = ε₀A/d. This is a hard-level question due to the derivation.
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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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