23-10-2017, 04:30 PM
24-10-2017, 04:42 PM
A practical electric power source which is a linear electric circuit may, according to Thevenin's theorem, be represented as an ideal voltage source in series with an impedance. This impedance is called the internal resistance of the source. When the power supply delivers current, the measured voltage output is less than the voltage without load; the difference is the voltage drop (the product of current and resistance) caused by the internal resistance. The concept of internal resistance applies to all types of electrical sources and is useful for analyzing many types of electrical circuits.