Question

IN Four identical metal plates, Plates 1 and 4 are connected by a connecting wire. A battery of emf V volts is connected between plates 2 and 3. The
electric field between plates 3 and 4 is 2V/Kd. Find the value of K.

Answer 1

The capacitance increases as the dielectric constant K>1.

(ii) Potential difference V=

C

Q

. As C increases and Q remains the same since the battery is disconnected, the p.d. between the plates decreases.

(iii) Electric field E=

d

V

where V is the p.d. and d the separation between the plates. As V decreases and d remains the same, electric field also decreases.

(iv) Energy stored in a capacitor U=

2

1

C

Q

2

. As Q is constant and C increases, U decreases.