Why does the voltage across the terminals of a cell or battery fall when it is delivering current?

The voltage across the terminals of a cell or battery falls when it is delivering current due to internal resistance. When current is drawn from a cell or battery, the flow of electrons through the internal components of the cell encounters resistance, which causes a drop in voltage. This internal resistance is caused by factors such as the resistance of the electrolyte, the resistance of the electrodes, and the resistance of the connections within the cell. As a result, the voltage across the terminals of the cell or battery decreases as current is drawn from it.

The voltage across the terminals of a cell or battery falls when it is delivering current because of internal resistance. Internal resistance is the resistance of the cell or battery's internal components, such as the electrolyte, electrodes, and terminals. When current flows through the cell or battery, it encounters this internal resistance, which causes a voltage drop. This voltage drop is known as the internal voltage drop.

The internal voltage drop is proportional to the current flowing through the cell or battery. This means that as the current increases, the voltage drop also increases. This is why the voltage across the terminals of a cell or battery falls when it is delivering current.

The internal resistance of a cell or battery can vary depending on a number of factors, such as the type of cell or battery, the age of the cell or battery, and the temperature of the cell or battery.