A capacitor of capacitance 15 pF15\text{ pF}15 pF consists of two parallel metal plates separated by an insulator of thickness 0.80 mm0.80\text{ mm}0.80 mm. The area of overlap between the plates is 2.4×10−4 m22.4 \times 10^{-4}\text{ m}^22.4×10−4 m2. Calculate the permittivity of the insulator between the capacitor plates.
permittivity = ................................... F m−1\text{F m}^{-1}F m−1
Fig. 21 shows a circuit.
Fig. 21
The capacitance of each capacitor is 1200 μF1200\ \mu\text{F}1200 μF. The resistance of the resistor RRR is 8.0 kΩ8.0\text{ k}\Omega8.0 kΩ. The cell has e.m.f. 6.0 V6.0\text{ V}6.0 V and negligible internal resistance.
Calculate the total capacitance CCC in the circuit.
CCC = ................................... μF\mu\text{F}μF
The switch S is closed at time t=0t = 0t=0. There is zero potential difference across the capacitors at t=0t = 0t=0. Calculate the potential difference VVV across the resistor at time t=7.2 st = 7.2\text{ s}t=7.2 s.
VVV = ................................... V\text{V}V
