A cell consists of electrodes and electrolyte. When it is connected to an external circuit it sends a current through it. What is meant by internal resistance of a cell?

A cell consists of electrodes and electrolyte. When it is connected to an external circuit it sends a current through it.What happens to the terminal voltage of the cell when it sends a current through the extemal circuit?

What is the current through this circuit?

Using a potentiometer how do you determine the internal resistance of a cell?

When a 12V battery is connected to resistor , 2.5 Ma current flows through the circuit . If so what is the resistance of the resistor ?