Answer to Question #318696 in Physics for mcc

Question

(a) Calculate the capacitance of a parallel-plate capacitor whose plates are 20 cm x 30 cm and are separated by a 1.0-mm air gap.

(b) what is the charge on each plate if a 12-V battery is connected across the two plates?

(c) What is the electric field between the plates?

Answer 1

(a)

$$C=\frac{\epsilon_0 A}{d}\\ =\frac{8.85*10^{-12}*0.2*0.3}{0.001}=5.31*10^{-10}\:\rm F$$

(b)

$$q=CV\\ =5.31*10^{-10}*12=6.37*10^{-9}\:\rm C$$

(c)

$$E=\frac{V}{d}\\ =\frac{12}{0.001}=12000\:\rm V/m$$