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Teacher/Instructor Jonathan Osbourne
Jonathan Osbourne

PhD., University of Maryland
Published author

Jonathan is a published author and recently completed a book on physics and applied mathematics.

Resistance is the relationship between potential difference and electric current generated. High resistance needs a large potential difference to generate an appreciable current. Electrons will generally flow through the path with the least resistance.

So let's talk about resistance. What is resistance? Resistance gives us the relationship between the potential difference that we apply and how much current we generate from that potential difference. So if I've got a high resistance, that means I need a very large potential difference to generate even a small amount of current. If I've got a small resistance, then that means even a tiny potential difference will generate an appreciable current. So the symbol for resistance is r, r for resistance and the unit is ohm. Alright.

So what is an ohm? One ohm and we use this strange horse shoe symbol for ohm, one ohm is equal to one volt per amp. And it's real easy to understand what resistance means just from this relationship.

If I've got a 5 ohm resistance, then it means I need 5 volts of potential difference to generate one amp of current. Alright. So, there's a nice analogy that I really like with resistance and resistors and that has to do with traffic flow. So I always like to think about resistance as like traffic lights. The more resistance you've got, the more traffic you've got, the less people would choose to take that road. If there's an alternate road that has less traffic lights, then more people will take that road than the one that's got all the traffic lights.

Alright. That's resistance.