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Featured Tiny Tweak in Teaching Basic Circuits

  1. Mar 24, 2017 #21
    One fine point is that "ground" is also referred to as " Common" meaning this part of the circuit has a common potential and removes from the mind a visual concept that could be confusing. The common connects many parts of a circuit together one of them usually being one of the terminals of the power source. Ground should be used for the common of a circuit that is physically connect to the earth. .
  2. Mar 24, 2017 #22
    As someone who is somewhat versed in Electronics, but only basic physics. I'll tell you what I was taught for what it's worth. Voltage IS the Potential. In a physics reference, it's the amount of force. Current is the amount of total volume (flow) available. The simplest idea is to always think of electricity like water flowing through a pipe. The size of the pipe, and the total flow determines the force. That being said. Potentials and Difference are ALWAYS relative, not absolute. A lot of the same math used to derive relative physics is used to derive electrical theories. Voltages can be dropped across resistive sources, but as stated. The voltage isn't "consumed" in some manner. It's still there, It's force is merely being dropped (held back if you will although somewhat inaccurate in description) by a relative resistance. The term "Common" is just that. It's a measurement point for taking readings where you connect the black probe of the DVM, scope, or whatever testing device your using. In no way should it ever be considered as a "Ground Point" or "At Ground Potential" when in fact a lot of times this isn't true. In cases where AC and DC are traveling together in a circuit (transistors and amplifiers usually). Potentials of complex circuits are usually determined by Thevenin's Theorems. Total current potentials are actually determined by Kirchoff's Law. Ohm's Laws are only used in the simplest of circuits for any analysis purposes. BTW: I left it alone for the most part, but my instructor first year summed it up quickly in class for those that "just couldn't get it". You either understand electronics concepts and theories going in, or your just another smuck trying to learn basic electrical theory so you can be a functional car mechanic.
  3. Mar 25, 2017 #23
    A good functional car smuck bills at $120.00 per hour around here.
  4. Apr 24, 2017 #24


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    Good at changing parts, one at a time until the fault disappears but not at analysing at the problem, processing the evidence and changing just one part to solve the problem. That $120.00 per hour is very often a rip off but what else can one do? The tools and analysis equipment are expensive and specialised so few of us can afford to DIY any more.
    I had a wonderful guy in Hove, who mended VW vehicles. He used to say "You don't need a new part yet. We'll do it at the next service". Not many like him around.
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