Resistivity
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- čas přidán 24. 08. 2024
- 017 - Resistivity
In this video Paul Andersen explains how the resistivity of a material opposes the flow of charge. Conductors (like metal) will have a low resistivity and insulators will have a high resistivity. Semiconductors will have a moderate resistivity. Since the resistivity is determined by the atomic and molecular structure it is affected by changes in temperature.
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"File:3 Resistors.jpg." Wikipedia, the Free Encyclopedia. Accessed May 16, 2014. en.wikipedia.or....
"File:3 Resistors.jpg." Wikipedia, the Free Encyclopedia. Accessed May 16, 2014. en.wikipedia.or....
"File:Polycrystalline Silicon Rod.jpg." Wikipedia, the Free Encyclopedia. Accessed May 16, 2014. en.wikipedia.or....
"File:Resistivity Geometry.png." Wikipedia, the Free Encyclopedia. Accessed May 16, 2014. en.wikipedia.or....
Lourenço, André Carvalho; Leandro M. 1/12 from Carbon-12, March 14, 2007. Own work. commons.wikimed....
PHGCOM. English: A 250kg Gold Bar in the Toi Gold Mine, 2007. Own work by uploader, Toi Mine. commons.wikimed....
At the very start you state "FLOW OF CHARGE" a couple' times....GREAT!!!! GREAT!!! I just had to stop after the 1st 25 seconds, to say how good it was to actually hear someone state what "current" actually was!
I know the world will never 'say it correctly",but MANY THANKS!!!
Whenever I hear "flow of current", I always, in the back of my head, think 'acceleration of charge'
--daLE
I cannot resist commenting. This is a good explanation of the concept. In fact, temperature is always a very important factor in any electronic circuit design. Semiconductors and other components are rated for specific temperature ranges and voltages. What wasn't covered here are the extremes, like super high-voltage arcing, thermal runaway and high-current heat convection, but that may be beyond the scope of this introduction. Thanks
i like to remember the equation as PLAR. PL=AR. Resistivity x Length = Area x Resistance
Another way is to remember the word"REPLA" (the word replay) where R = resistance, E for equal sign, P for resistivity symbol (rho), L and A for length and area respectively
R = PL/A
@@ammarkhan2927 Needed something like this to help me remember. Thank you 🤝
I study R=Resistivity ×length ÷Area
Resistivity is constant and inversely to conductivity
It was a short video but easy to understand it is clarified Thanks Sir... STAY SAFE DUE TO CORONAVIRUS
Thank you man
Learning so much core knowledge from your videos.
Thank you so much, your videos are really helpful for us college students, I'm going to pass materials science because of you!
Excellent Video. Straight to the point.
Fantastic .
Massive help ..
Helpful.
Thank you
Hey thanks heaps for ALL your vids, super helpful and legit a life saver, especially the bio vids :))
Don't RESIST reading this aha
Thanks for supporting science keep going I'd like to make a request for some thing I'd want you to explain if I may.
thanks for helping...
great
Ty this helped with my homework.
1:22 Changing the amount of material doesn't change the resistivity?? I don't think you meant that, but it sounds like that.
thanks
But if you increase the temperature, should not current flow increase due to excitement?
You asked this 7 years ago, but it might help to someone else. Increasing the temperature in metals in many cases leads to allotropy, which means the atomic structures of the metal changes. The main reason of this is because the heat transfers as kinetic energy into the atoms, so they start vibrating with a larger and larger amplitude, so atomic bonds that was stable enough on a lower temperature are not stable enough anymore, and as a result they rearrange into a new one. This change can occur more than once until you reach the melting point of the metal. Partly this change is responsible for the increasing resistivity, but the main reason is the increased atomic vibration.
Electrons (the current) go between the atoms, but because the atoms are more fidgety, electrons can not go so easily, they always bump into the more and more fidgety atoms of the metals atomic structure (called crystal lattice). And of course electrons themselves are more speedy as well, so it's like in a video game where the player try to run all the time, because he believes he is playing an action game but he is actually playing an RPG and he is in a small room, but he still try to run like hell because he needs to finish the game in 3 days otherwise something bad happens. So that"s what the electrons do as the temperature rises, and they are not too successful to handle the situation. They just bump to everything and to each other with full speed. So that is the main reason when it comes to metals.
In semi conductors it happens the other way around. In very simple terms, electrons can not go easily freely between atoms when the metal is at room temperature, they just don't have enough energy. There are obstacles keeping them back running around. But as the temperature rises they gain enough energy to do that, so they start running around freely, and the metal becomes a conductor.
My teacher sent me this..... my own physics teacher sent me this
why not! i'm also physics teacher and i'm gonna watch this together with my class today :)
@@user-fl4ti7ir8e been 3 years forgot the reason
🥇
Leave a like if you're taking Mr. Yarbroughs AP physics class and are watching all of these last minute.
Not at all
Not good
great