Question

Explain what would happen if in the capacitor given in Exercise 2.8, a 3 mm thick mica sheet (of dielectric constant = 6) were inserted between the plates,
(a) While the voltage supply remained connected.
(b) After the supply was disconnected.

Answer 1

(a) Dielectric constant of the mica sheet, k = 6
If voltage supply remained connected, voltage between two plates will be constant.
Supply voltage, V = 100 V
Initial capacitance, C = 1.771 × 10⁻¹¹ F
New capacitance, C1 = kC = 6 × 1.771 × 10⁻¹¹ F = 106 pF
New charge, q1 = C₁V = 106 × 100 pC = 1.06 × 10^–8 C
Potential across the plates remains 100 V.