Intro to Electrical Resistance, Resistors, and Resistivity | Doc Physics

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The world needs more people like you. Thank you so much. :')

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You seem like a good teacher, very interactive and enthusiastic

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so my exam is tomorrow and i decide to watch some youtube videos cause I'm dead sleepy and i some how land on this and damn i have never been more awake! thanks dude!

[@Crowalesce]

Your videos are absolutely amazing! Trying to learn electronics with little to no background is difficult, but your explanations are great. Thank you for posting all of these!

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[@victordolman2646]

Great video. Love the audience participation. Just a note from a Dutchman: the discoverer of superconductivity is called Heike Kamerlingh Onnes. Heike is his first name, and Kamerlingh Onnes is his last name. It's a double last name, which is not uncommon in the Netherlands. It usually means that somewhere in the family tree there is some nobility (but not necessarily). Calling him just Onnes is wrong and sounds completely weird to a Dutchman. Kamerlingh Onnes was a pure experimentalist whose motto was: "Door meten tot weten" (through measuring to knowing). The 'me' in 'meten' and the 'we' in 'weten' are pronounced to thyme with the English may and way, not me and we. When I was in school there was an elderly technical assistant who, as a boy, had worked in the lab of Kamerlingh Onnes. We heard some of his stories, and as a consequence to me that past does not feel all that long ago.

[@MysticMD]

Thank you so much! I cannot do physics so well without your (and many other youtubers') videos.

[@DocSchuster]

You are welcome!

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when i want fun in my study, i just find you in my mind!! well done!

[@DocSchuster]

Thanks, buddy! Keep up the hard work, yo. Make magazine has a book on electronics that I really like, too. You should also get some broken electronics from the trash and take them apart. Fun and free!

[@62yaz]

This helped so much in clarifying my knowledge before I do my test

[@TK-ld1jj]

Awesome teacher👍 appreciate your work

[@Venkatesh12774]

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you're an amazing teacher!

[@rsapu22]

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[@user-yh8jr8tk9z]

So so so so helpful, thank you

[@carlwithers3986]

very good

[@bushrashaikh5240]

Where was you tube, n this channel when I was a college student!! Where??!!!

[@mvsprabash]

Good explanation Thank you

[@NoName-eg8bx]

Amazing for ever *_*

[@hanohbl9341]

hey do you have some sort of an online course where you go a bit deeper into specific problems? I really like your vids and it's helping me go through my physics 2 course at uni

[@arkaprobhaghosh5664]

The explanation was very good sir

[@meandsunset]

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[@faresahmed9338]

very helpful

[@joebastulli]

Very helpful

[@penniesilver7975]

thank you so much this really helped!

[@ExtremeEngineering]

thanks

[@netauri123]

how is it possible to measure that current in the circular super conductor without significant changes on it?

[@DocSchuster]

netauri123 Its magnetic field causes a precession of nuclear spins at radio frequencies. The precession can be measured using a process called Nuclear Magnetic Resonance, which is the technology behind MRI's.

[@nicholasorton17]

Thanks you so much

[@stvnpatt]

Hi Doc Schuster I have a question, two copper wires, one twice the length of the other. How do the resistivities of the two wires compare? The answer is both wires have the same resistivity? Are you able to explain this for me?

[@georgemamouzellos4647]

Resistivity is a property of a substance, while resistance is a property of an object. Copper is a substance. A wire is an object. A wire object made of the substance called copper will have an overall resistance, while the copper substance itself that the wire is made of has a resistivity that does not change no matter how big or small a wire you make out of it. If you use longer sentences, it becomes easier to understand. eg "copper is a substance, that has a resistivity of X. If you make an object like a wire ,then the wire has an overall electrical resistance that depends on its shape, temperature, and on the electrical resistivity of the substance that it is made of". Hope that cleared things up for you.

[@truebark3329]

Hmmm.. If V = IR, then if i have a 9V battery and want to put enough resistance so that the current is zero then the total resistance i will need to apply will be :- 9v = 0A*R , which would be 9/0 which is equal to not defined. So does that means I can't do that?

[@fathyhusseiny4484]

what does it meanα{R(T) = R(T0) * [ 1 + a(T - T0) ] = R(T0) + R(T0)*a*(T - T0) ) is negative for carbon and silicon

[@wanpingbai]

Saw resistance with units ohm-m^2 sometimes. How to understand that? And what value (like cross section?) is needed to convert it back to ohm?

[@DocSchuster]

Wanping Bai That's related to resistivity, and I would imagine that cross section would get you back home!

[@georgemamouzellos4647]

The flow of electrical current along a wire depends on the substance that the wire is made of, and the surface area of the wire. Of course the mass, volume, temperature, grain orientation etc play a role as well, but the surface area is the most important in general electricity. Regarding what you said above, with units of ohm-m^2, what is being referred to is how much resistance there is per unit surface area. So, to "convert back to ohm" as you said, you simply divide that value, which is in units of ohm-m^2, by the surface area of whatever it is being referred to, using units of m^2.

[@bucherregaldomi9084]

How big is the current in a superconductor? I mean, it can't be infinite, right?

[@DocSchuster]

Good question. On the contrary, we can conclude that since there can't be an infinite current, there must also never be a potential difference between points on a superconductor.

[@SauceChef]

Does a superconductor have a lower resistance than silver?

[@DocSchuster]

Fish Ed Mr. Ed, a superconductor has NO resistance. Seein' as how silver does have resistance, YOU BET.

[@SauceChef]

Doc Schuster Heh, I thought so. Thanks.

[@simran_kaur963]

listen bro can tell me only resistance in simple word m student

[@pec1739]

i wish i was in this school, sigh

[@dillonberger4036]

"Just your average off-the-shelf Niobium"

[@sunildeore8935]

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[@sunildeore8935]

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[@DocSchuster]

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