What's the formula for calculating generators internal resistance in a circuit with a load?
I am given the load resistance and the voltage sources voltage. What's next?
I have tried number of ways in calculating the internal resistance of my power supply and I always get different values at different voltages.
First I measured open loop voltage of PS (Ug) then I measured voltage on output with load applied (Ul). The voltage drop on internal resistance should then be equal to: Urg = Ug - Ul , then I measured the current drawn from PS and put it in equation: Rg = Urg / I
But it doesn't seem to be the right formula, because when I apply different voltage I get different internal resistance, which should be the same all time...