Take the following circuit:

enter image description here

If I do a simulation of this circuit I get this graph:

enter image description here

The strange thing is that in the simulator it gives the same voltage sine wave in the circuit, near the voltage source and near the capacitor.

In real circuit is it the same? Even if the wire is long between the voltage source and the capacitor?

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    \$\begingroup\$ Real wires have inductance, capacitance, and resistance that you haven't modelled here. \$\endgroup\$ – Hearth May 25 '19 at 13:28
  • \$\begingroup\$ but for the vlaues you used, these will most certainly not ever play a role. How can you do a spice simulation without having thought about what a connection in a schematic means? It just literally means "these two points are somehow connected. We model this connection to be loss- and lengthless", Nmaster88. \$\endgroup\$ – Marcus Müller May 25 '19 at 13:29

What looks like a 'line' running from your voltage source, past your resistors, to your capacitor isn't. It's a NODE. The simulator models it as a single connection point, with a single voltage. You could redraw that circuit by changing the order of the components, making that line wiggly or very long, and the simulator will treat it in exactly the same way.

If you want to describe a physical conductor, perhaps 1m of copper wire 1mm2 area, then as a first order approximation, valid for DC, you can model that as a series resistor of 0.017ohms.

If you want better (more realistic, matching what real wires do at higher frequencies) models, then adding some series inductance, or using a transmission line of a suitable impedance would be the things to do.

We always try to use the simplest model that describes what we need describing, and nothing more.

| improve this answer | |
  • \$\begingroup\$ Yes I think this is what I'm looking for, I will do a model that has some series resistance and inductance. \$\endgroup\$ – Nmaster88 May 25 '19 at 18:43

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