Questions tagged [resistance]
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.
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Correct formula for LED current-limiting resistor?
I'm trying to work out what value resistor to use in a LED circuit. The equation I'd use to do this is:
$$ R = \frac{V_{cc} - V_f}{I_f} $$
Seems logical, and makes complete sense. The answers to the ...
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How do I calculate the resistor value for a simple LED circuit?
I have a simple circuit:
The max rating (current) of the LED is 30mA.
How can I work out what the resistance of the resistor needs to be? By using ohm's law I found it to be \$3V/0.03A = 100 \Omega\$...
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I/O Resistance of common source MOSFET with source degeneration
Common Source MOSFET with source degenerations looks like this
I am a bit confused about different input and output resistance statements (provided by different sources).
Some of them say that ...
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How do you determine the effective resistance of a finite grid of resistors?
Disclaimer: I am a geophysicist with limited electrical engineering background. I am not sure if this problem is incredibly easy, incredibly complex, or completely nonsensical.
My goal: Determine the ...
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Does a diode really follow Ohm's Law?
Does a diode really follow Ohm's Law?
Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points.
Introducing the constant ...
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Common drain JFET output resistance "problem"
The output resistance of small signal model for common drain JFET amplifier equals $$ \frac{1}{g_\text{m}} || R_{\text{ds(on)}} \parallel R_\text{S} $$ and since $$ R_{\text{ds(on)}} =\frac{1}{g_\text{...
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Why can sticking fingers in an electric outlet kill you?
I just wanted to learn some differences between volts, amps, ohms and so forth and came up with this question. If your skin has 100k ohms resistance and the outlet is 220v wouldn't the current flowing ...
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what is the equivalent resistance of this configuration? [closed]
consider the blocks as resistance and the numbers as their respective resistance.count it's equivalent resistance across A and B.
I just want some hints.this is not my homework problem.I am just ...
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Is the electric field in a wire constant?
If \$V=I\cdot R\$ according to Ohm's Law, that implies that \$\frac{\mathrm dV}{ \mathrm dx} = \frac{I \rho}A\$ across an infinitesimal length of conductor, which is constant at all points along the ...
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Voltage drop across a single resistor and across two resistors
I have been having difficulty understanding voltage drops across resistors. Now, I know the theory and how to apply Ohm's law.
The question is why does the voltage drop across resistors of the same ...
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Does an ATX PSU's PS_ON Signal Require Resistance
As the title suggests; when connecting the PS_On signal directly to ground in order to switch on an ATX PSU, is there a required amount of resistance?
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To try to clarify my particular problem; I ...
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How to solve infinite grid with the observing terminals at diagonal of infinite square matrix?
The answer given is 2/3ohm solution is not given but I can expect how they got that answer but can't justify the way.
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Why does water short out PCBs? (i.e. Why doesn't electricity follow the path of least resistance?)
If copper is more conductive than water (at any reasonable PH), submerging copper electronic circuits in should have no effect, as the electricity should continue to follow the path of least ...
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Resistors with ends of the same colour
I know the values of resistors if they are gold-colored at the end. When both ends are the same, such as brown-o-p-brown and red-x-y-z-red, I am in problems. How to know which side has the last colour ...
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finding the output resistance of bjt folded cascode
I am being asked to find the output resistance of following BJT cascode amplifier, from "Microelectronic Circuits" by Sedra and Smith, 7th edition, problem 8.80.a on page 588.
Now I decided to ...
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