21 Ways of Stating Ohm's Law August 11, 2015 16:31

Ohm's law is the key to understanding basic electronics. It describes how the three elements of electricity—current, voltage, and resistance—relate to each other. Ohm's law can be expressed as an equation three ways: 

  1. I (current) = V/R
  2. V = IR
  3. R = V/I

Which is crystal clear if you've studied electronics for years. Most of us need to hear it rephrased in plain language dozens of different ways before it clicks.

All of the statements below are simply ways of restating the equations above. Each one is pretty dense and many will be counter-intuitive. Take your time to unpack them, and leave your questions in the comments if anything doesn't make sense.

I hope one of them makes Ohm's Law click for you.

  1. Voltage is how much current will flow through a conductor of a certain resistance.
  2. Voltage is the resistance of a conductor given a certain current.
  3. Resistance is how much current will flow given a certain voltage.
  4. Resistance is how much voltage will be generated by a certain current.
  5. Current is how much voltage will be generated by a certain resistance.
  6. Resistance is the ratio between voltage and current.
  7. Current is the resistance of a conductor given a certain voltage.
  8. Resistance is how easily voltage can increase current.
  9. Voltage makes current flow through a conductor.
  10. If voltage is fixed, increasing resistance will decrease current.
  11. If current is fixed, increasing resistance will increase voltage.
  12. If resistance is fixed, increasing voltage will increase current.
  13. If resistance is fixed, increasing current will increase voltage.
  14. Current is proportional to voltage; resistance is the constant of proportionality.
  15. Without any of the three, there’s no electricity. (Try putting zero in any of the equations.)
  16. Current moving through a conductor creates voltage.
  17. You can’t have voltage without current, current without resistance, etc.
  18. “Danger: High Voltage!” could also be correctly written “Danger: High Current and Resistance!”
  19. If resistance is very low, you can get a ton of current with a very low voltage. (eg. 1 Volt / 0.001 Ohms = 1,000 Amps).
  20. If resistance is very high, you get very little current even with very high voltage (eg. 1 Volt / 1M Ohms = 1 micro Amp).
  21. If you know two, you can always figure out the third.