Concepts Of Physics MCQ Edition [Volume 2]PhysicsCapacitors
A parallel-plate capacitor with a plate area of 20 cm ^2 and a separation of 1.00 mm between the plates is connected to a 12.0 V battery. The plates are subsequently pulled apart to increase the separation to 2.0 mm . Calculate the charge flown through the circuit during this process.
Options
- A1.06 10⁻¹⁰ C
- B0.53 10⁻¹⁰ C
- C3.18 10⁻¹⁰ C
- D2.12 10⁻¹⁰ C
Correct answer
A. 1.06 10⁻¹⁰ C
Step-by-step solution
The initial capacitance of the parallel-plate capacitor is given by C₁ = ₀ A d₁ . When the plates are pulled apart to a separation d₂ , the final capacitance becomes C₂ = ₀ A d₂ . Since the battery remains connected, the potential difference V across the capacitor is constant. The initial charge on the capacitor is Q₁ = C₁ V and the final charge is Q₂ = C₂ V . The charge flown through the circuit is the difference between the initial and final charges: Q = Q₁ - Q₂ = (C₁ - C₂) V Q = ₀ A V ( 1 d₁ - 1 d₂ ) Substitutin