Question

A capacitor is charged and a battery is disconnected. Now the distance between the plates is increased slightly
A. Forces between the plates will decrease
B. The potential energy of the capacitor will decrease
C. Potential difference between the plates will decrease
D. Potential difference between the plates will increase

Answer 1

Hint:- A capacitor is an electronic device that stores energy in an electric field. A capacitor consists of two metal plates that are separated by an insulator. The effect of a capacitor is known as capacitance. Capacitors look like batteries but they perform different functions in a circuit.

Complete step-by-step solution :Step I:
When a voltage is applied over the plates of a capacitor, the charge starts moving. But since the two plates are separated by an insulator, charge cannot cross the plates. Therefore, positive charge accumulates at one plate and negative charge accumulates at the second plate.
Step II:
Charge stored on the capacitor remains the same if the battery is disconnected. So the electric field will be the same between the plates. The potential difference is the work done to move a unit positive charge from one point to another. Also in case of a uniform electric field, potential difference is given by
$V = E.d$
Where E is the electric field strength
V is the potential difference
d is the distance between two points.
Step III:
Since the electric field is uniform even after the battery is disconnected, the potential difference between the plates will increase if the distance between the plates increases.
Option D is the right answer.

Note:- It is to be noted that the terms electric potential and potential difference are not the same. They are completely different. Electric potential is the ability of a charged body to do work. If a body is charged, then either the electrons are getting removed or are supplied. This work is done by the body which is stored in the form of electric potential.