Explain why the electromotive of a dry cell drops if a large current is drawn for a short time and then recovers if allowed to rest?

The electromotive force (EMF) of a dry cell drops when a large current is drawn for a short time because the internal resistance of the cell causes a voltage drop across it. When a large current is drawn, the internal resistance of the cell causes a significant voltage drop, leading to a decrease in the overall EMF of the cell.

When the cell is allowed to rest, the internal resistance has time to recover and the voltage drop across it decreases. This allows the EMF of the cell to recover to its original value. Essentially, the internal resistance of the cell needs time to recover after being subjected to a large current draw, which is why the EMF drops initially but then recovers when the cell is allowed to rest.

The electromotive force (EMF) of a dry cell drops if a large current is drawn for a short time because the cell's internal resistance limits the amount of current that can flow. When a large current is drawn, the voltage drop across the cell's internal resistance increases, which reduces the voltage available to power the external circuit. This causes the EMF of the cell to drop.

If the cell is allowed to rest, the voltage will recover because the cell's internal resistance will decrease. This is because the cell's internal resistance is caused by the buildup of ions on the electrodes, and this buildup can be reduced by allowing the cell to rest. When the cell's internal resistance decreases, the voltage drop across the cell's internal resistance decreases, which increases the voltage available to power the external circuit. This causes the EMF of the cell to recover.