modified 10 months ago

Negative voltage is a dum-dum

00:36:04

I struggle with the concept of negative voltages / currents.   They are really just voltages / currents in the opposite direction (compared to positive).  Putting it in terms of positive and negative confuses me.   Here's why: the visualization shows that this circuit behaves the same way regardless of the position of the switches, but the math represented in the graphs looks radically different.  Aarrgghhh!!! 

published 9 years ago

thebugger

9 years ago

Math is quite the same. You just add a ➖ on every negative voltage and a ➕ on every positive one. The thing that separates them as two distinct types of voltages is the ground reference. In every circuit (almost without exclusion) you can ground either the positive rail or the negative one. People are used to grounding the negative rail because circuit analysis is simpler, due to the conventional current flow. It actually doesn't really matter because the voltage is a parametric unit |-V| |V|. Basically your voltmeter will always read a positive value despite whether your voltage is negative or positive.

thebugger

9 years ago

http://everycircuit.com/circuit/5123492319592448

thebugger

9 years ago

*the word is not parametric i think its modular

Bushmills

9 years ago

A voltage is relative, measured against ground level. Increase voltage of ground, and voltage of your measuring point gets smaller, or even negative when voltage of ground exceeds the voltage of your measuring point.

Bushmills

9 years ago

To illustrate this idea, please look at http://everycircuit.com/circuit/6169323197956096

mtobot

9 years ago

Thanks for the feedback. I can't say I still fully understand it, but every little bit helps. :)

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