Question

If X & Y are two parallel plate capacitors having the same area of plates & same separation between the plates.X has air between the plates & Y contains a dielectric medium of K=5.And potential difference between the plates of X & Y is 10V & 2V.Find the ratio of electrostatic energy stored in X & Y

Answer 1

Explanation:

1. C¹=C and C²=5C
2. use formula for energy stored 1/2CV²
3. you will get 125/1

Answer 2

Since the total charge that have appeared before and after removing the battery is same.

Original charge= (2 x C + C) x V as the capacitors are connected in parallel.

After removing the battery:

New capacitance = (K x C + 2 x C) x V'.

Where V' is the final potential difference.

After equating we get:

V'= 3*V/(K+2)  

Thus the potential difference across the capacitor will become

V'= 3*V/(K+2)