Determination of internal resistance of a cell

A practical electrical power source which is a linear electric circuit may, according to Thévenin’s theorem, be represented as an ideal voltage source in series with an impedance. This resistance is termed the internal resistance of the source. When the power source delivers current, the measured e.m.f. (voltage output) is lower than the no-load voltage; the difference is the voltage (the product of current and resistance) drop caused by the internal resistance. The concept of internal resistance applies to all kinds of electrical sources and is useful for analyzing many types of electrical circuits. Internal resistance can be caused by a number of outcomes, though a possible cause is by interior chemical installment. When thermal energy is applied to provide the current, that applied energy is most of the power source’s energy which produces the chemicals. The load current is delivered in a lap and returns to the battery (voltage source) and then performs resistance.