A parallel plate capacitor is charged and disconnected. If a dielectric slab (εr = 2) is inserted filling half the gap, the capacitance:
Correct answer: C. Increases but doesn't double
- A. Doubles
- B. Halves
- C. Increases but doesn't double
- D. Remains unchanged
Explanation
The system acts as two capacitors in series: one with dielectric (C₁ = 2ε₀A/(d/2)) and one without (C₂ = ε₀A/(d/2)). Equivalent capacitance is Ceq= (C₁C₂)/(C₁ + C₂), which increases but is less than 2C due to series combination.
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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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