Question

 What is the capacitance of an empty parallel-plate capacitor with metal plates that each 2

have an area of 1.00 m , separated by 1.00 mm?. How much charge is stored in this

capacitor if a voltage of 3.00 x 103 V is applied to it?

Answer 1

The capacitance of a parallel plate capacitor

$$C=\frac{\epsilon_0A}{d}=\frac{8.85*10^{-12}*1.00}{1.00*10^{-3}}=8.85*10^{-9}\:\rm F$$

The energy stored in capacitor

$$W=\frac{CV^2}{2}\\ =\frac{8.85*10^{-9}\:\rm F*(3.00*10^3\:V)^2}{2}=0.0797\:\rm J$$