Review Conceptual Example 11 before attempting this problem. An empty capacitor is connected to a 9V battery and charged up. The capacitor is then disconnected from the battery, and a slab of dielectric material (k=3)is inserted between the plates.

Question

(a) Find the amount by which the potential difference across the plates changes.

(b) Find the final potential difference.

Answer 1

The capacitance C triples since it is proportional to k, the charge stays the same and the voltage becomes Vo/3 = 3V.

The voltage drop is 6V