result of this accumulation of charges on this plate it becomes positively charged (called anode). Negative ions move in a direction opposite to the motion of positive ions and accumulate on the other plate. As a result of this the plate becomes negatively charged (called cathode). This accumulation of different charges on respective plates continues till both plates are sufficiently charged.

But the ions in motion experience another force when sufficient number of charges are accumulated on the plates. Let us call this force as electric force (Fe ). The direction of this force is opposite to the direction of chemical force Fc and the magnitude of this force depends on the amount of charge accumulated on the plates.

The motion of ions continue towards their respective plates if the chemical force Fc is stronger than electric force Fe . See figure 7. The accumulation of charges on plates is continuous till the electric force Fe becomes equal to chemical force Fc . At this situation there will not be any motion in ions due to balance of forces Fe and Fc . It is shown in figure 8. The new battery that we buy from the shop is at a stage where the ions in the electrolyte are under the influence of balanced forces. See figure 9. This is the reason for the constant potential difference between the terminals of a battery.

The amount of charge accumulated on the plates depends on nature of the chemical used in the battery.

• What happens when the battery is connected in a circuit?

When a conducting wire is connected to the terminals of the battery, a potential difference is created between the ends of the conductor. This potential difference sets up an electric field throughout the conductor (the direction of electric field is from positive terminal to negative terminal in the conductor).