In a parallel plate capacitor with air between the plates, each plate has an area of 6 × 10−3 m2 and the separation between the plates is 3 mm. (i) Calculate the capacitance of the capacitor. (ii) If this capacitor is connected to 100 V supply, what would be the charge on each plate? (iii) How would charge on the plates be affected, if a 3 mm thick mica sheet of K = 6 is inserted between the plates while the voltage supply remains connected?



(i) Capacitance, C=ε0Ad=8.85×10-12×6 × 10−33× 10−4=17.7× 10−11 F (ii) Charge, Q=CV=17.7×10-11×100=17.7×10-9 C
(iii) Now, C' = KC ∴ Q' = KQ = 10.62 × 10−8 C