How does the internal resistance increase?

Hint: In order to answer this question, first we will discuss how and in which case the internal resistance increases and then we will explain about the internal resistance. And atlast we will discuss when we need to consider the internal resistance.

Complete step-by-step solution:
When it comes to determining how to obtain a source of electrical energy to deliver maximum power to an electrical device (the load) attached to it, the source's internal resistance is critical. In order to minimise the amount of current that would flow in the event of an inadvertent short-circuit, high-voltage power supply must have an exceptionally high internal resistance. When the distance between two electrodes is increased, the internal resistance of a battery cell increases. The electrolyte content decreases when the battery is depleted, eventually becoming pure water when the battery is totally discharged. During discharge, the battery resistance rises due to the change in electrolyte content.
The internal resistance of a cell grows with the gap between the plates because the resistance of a conductor increases with its length. The resistance of a conductor is proportional to its cross-sectional area. As a result, as the common area between the plates decreases, the internal resistance of a cell increases.
According to Thévenin's theorem, a practical electrical power source that is a linear electric circuit can be described as an ideal voltage source in series with an impedance. The source's internal resistance is the name for this impedance. The measured voltage output is lower than the no-load voltage when the power source delivers current; the difference represents the voltage drop (the product of current and resistance) induced by the internal resistance. Internal resistance is a notion that applies to all types of electrical sources and can be used to analyse a variety of electrical circuits.
Or in the simple words, when the circuit gets because of electrolyte and electrodes present in the battery/cell, it is the resistance (opposing force) in the passage of electricity. It can be found in the cell or battery.

Note: When determining whether a cell is suitable for usage in a certain circuit, the internal resistance must be taken into account. The external resistance of the cell must be significantly bigger than its interior resistance for maximum effectiveness.