A measure of how much a conductor opposes current flowing through it. It can also refer to a part of a circuit, which has a non-negligible resistance value.
Questions tagged [resistance]
1802 questions
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Why does Ohm's law not work for vacuum cleaners?
I have been learning about Ohm's law and testing the resistance across the plug of my household appliances and calculating the current.
For example, my kettle was 22 ohms (10.45 amperes) and is protected by a 13 A fuse.
This makes sense, and I'm…
Dominic Edwards
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How to make a dummy load of 1000W - 2000W?
I need to check a 48V battery with dummy loads of 1000-2000 watts for 5-10 minutes.
Perhaps using Nichrome wire, i can wrap some around a fire brick submerged in plenty of water and adjust the load by changing the length used?
bandybabboon
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What is negative Resistance
I have heard some people talk a bit about negative resistance, but I have never really understood it. What is negative resistance?
skyler
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How can I make 20-200 ohm variable resistor look like a 20-240 ohm resistor?
I have a fuel sender in my kit car that goes from 20R to earth (full) to 200R (empty). Unfortunately the gauge (constant current source, measuring resistance to earth?) expects empty to be 240 ohms, so displays '1/4 full' when empty.
What is the…
Stuart Leask
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Do resistors of same color code but different size have the same resistivity?
Picture has three resistors with the same color code (in this case brown-black-black) but different sizes.
My question is if they have the same resistivity because I know resistivity is indicated by color code.
manludo
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Resistance, and learning for beginners
I am building an electrified "fence" of sorts to keep slugs out of my raised garden beds. The "fence" consists of two 18ga galvanized steel wires, stapled to wood and connected to a 9V battery. The circuit is open until the slug touches both wires,…
Tyler V.
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Is heating element resistance linear?
I know light bulbs resistance varies depending on heat. What about heating elements?
Would 2000W heating element have 26.45 Ohm (230V / 26.45 Ohm = 8.7A, so 8.7A * 230V = 2000W) resistance both in room temperatures and at 100 C degrees?
Ri Di
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Wye-delta transform derivation
I have been reading about the Delta-Wye and Wye-Delta transforms for resistors, and I was curious as to how the equations for the Delta-Wye and Wye-Delta transforms are formed. I managed to isolate the variables for \$R_a\$, \$R_b\$, and \$R_c\$…
hedgepig
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What does "OC" mean?
My Bluegiga WT-32 manual ("Stereo CODEC ADC characteristics" table) says:
Allowed Load --> Resistive, min.:16(8)Ω , max.: OC
What does OC mean in this case?
Radon
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Can Resistance of wires be ignored?
I'm trying to calculate the internal resistance of my rechargeable batteries and haven't got a single battery holder so using I am having to using Banana plugs and Crocodile clips for holding my resistor. Then holding the banana clip on the…
Dean
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Isn't resistance a constant thing?
I have read that resistance is proportional to resistivity and length of the material and inversely proportional to the area of the material.
Doesn't that make resistance a constant thing?
Then I read that under breakdown of material and in things…
Alex
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Why can a shorted resistor be ignored?
I am having a little trouble understanding what results from short circuiting.
The bottom circuit is the one we are given in the question, and we are asked to obtain the Norton equivalent. The above picture is the worked solution.
I don't quite get…
sebajun
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Decade resistance box with BCD-type rotary switches
I'm looking at building my own decade resistance box, but the typical rotary switches are... quite expensive. They seem to be the most expensive part of the entire project. Whether I choose a real rotary switch or a DIP switch or even a thumbwheel…
tummychow
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Why does a larger wire cross section mean less atom-electron collisions when there must be more atoms, too?
Regarding how resistance varies with diameter I've read this simple explanation on Quora:
As electrons move across a wire, they constantly collide with atoms making up a wire. These collisions impede the flow of electrons and are what cause the…
yot
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Why is the impedance in the parallel resonant circuit maximum at resonance?
Why is the impedance in the parallel resonant circuit maximum at the resonant frequency?
For example if we have two resistors in parallel the equivalent resistance is less than the values of the resistors in the circuit. Isn't this similar to the…
jht
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