# Measuring the effect of a resistor

In an idealized model, the voltage at node1 is the same as the voltage at node2. However, in reality waves take time to travel and the voltage at node1 will not be identical to the voltage at node2. I was wondering how to choose the component values and wire lengths such that I can observe a different voltage at node1 and at node2.

• However, in reality waves take time to travel and the voltage at node1 will not be identical to the voltage at node2 Why not? Your model does not show any time-dependent components so there can be no delay. But this just a model. If you actually measure the voltages, is the model still valid? If yes then there still are no delays. So the answer must be no: the model is invalid. What do you think needs to be added? Only if you realize what the actual situation is (make a more refined model) can you properly evaluate this. First calculation to do: how much delay will there be? – Bimpelrekkie Dec 19 '18 at 9:48
• Thanks for the hint, a resistor can be modelled by an inductance in series with the parallel of a resistor and a capacitor. However, this model still would not capture the difference between the two circuits. Could you provide a more explicit hint? – Al Learner Dec 19 '18 at 9:58
• What I was referring to is that you will add some capacitance to the circuit if you measure it on the bench. Then that capacitance and the resistors result in RC time delays. But that's not what you are looking for I think. You will need to educate yourself on transmission lines because that where we consider wires to have time delays: en.wikipedia.org/wiki/Transmission_line Note how transmission lines are just wires but seen as distributed inductance and capacitance. – Bimpelrekkie Dec 19 '18 at 10:02
• "In an idealized model, the two circuits in the drawing are the same", in what sense? Since they are not equivalent. – Harry Svensson Dec 19 '18 at 10:19
• See ip.cadence.com/uploads/1012/Transmission_Line_WP_Final_0416-pdf for info on modelling a transmission line versus an ideal wire. – crj11 Dec 19 '18 at 14:40