Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [ohms-law]

A well known relationship that describes the relationship between Voltage and current through a device's resistance expressed mathematically as V= IR. This formula says that voltage across the device is equal to the current through the device multiplied by the resistance.

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Why do we need resistors in led

I've researched and it says that resistors limit the current flowing through the LED. But this statement confuses me because we know that in a series circuit, the current is constant at every point, so how come a resistor can limit the current…
vvavepacket
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Does Ohm's law always apply at any instantaneous point in time?

I often see people saying "Ohm's law doesn't apply here", usually in relation to AC circuits and diodes. They describe certain situations as being "non-Ohmic". My understanding of Ohm's law is that it always applies all the time, only it's sometimes…
Clonkex
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Is it true that not all components obey Ohm's law?

After explaining Ohm's law to someone who knew nothing about electronics, I was corrected by another guy, pointing out that not all components obey Ohm's law. I replied with the usual "I know, that's why I said in a simple resistive…
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I do not understand what power actually is

I realize this is probably a super common question, but I have to put it in my own words. I try to understand ohm's law with the water analogy. Two tanks with water, one with a higher level than the other, and a pipe connecting the two of them.…
Kelsie
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How can current-limiting supplies be possible?

Knowing Ohm's law, the current drawn is directly proportional to the resistance. In some power supplies, you can limit the current. Let's say the voltage is 12 volts, it supplies 1 amp, and the resistance is 8 ohms. The current going through should…
skyler
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Batteries have zero voltage

According to Ohm's law V=IR. This means that if the current is zero there is no voltage. Does this mean also that an unplugged battery has zero voltage? Then why does it say otherwise in the package. In other words: What does it mean that a battery…
Ambesh
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How do ohm meters measure high resistances?

I'm sorry if this is a stupid question, but I'm an apprentice and this doesn't make sense to me. I'm given to understand that an ohm meter measures resistance by passing a small current through a circuit and then internally calculating the…
Srmass
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When does a resistor affect current and voltage?

I was playing around with a computer power supply and some resistors and noticed that raising the ohmage decreased the amperage but the voltage was unaffected. Does this mean that voltage is a constant in V=IR. How can you change the voltage with…
Rhezner
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What's the correct term to describe a conductor which doesn't always obey Ohm's law?

Non-ohmic comes to mind, but that gives an impression that the conductor never satisfies Ohm's law. Is there a better term which describes a conductor which might satisfy Ohm's law at certain voltages and temperatures, but not at others.
Ashwin Phatak
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Can I use V=IR in the analysis of AC circuits?

My textbooks usually just assert this relation so I don't really know when it doesn't apply. EDIT: Reflecting on this question, I wanted to clarify that I wanted to know if Ohm's Law is valid for the analysis of time-varying current/time varying…
Minh Tran
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Is Ohm's Law always exactly true even at the microscopic level?

My probability textbook introduction just mentioned that Ohm's Law is not always precisely true at the microscopic level. How is this possible? What is causing this to happen?
codedude
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Voltage drop measurement result doesn't match my theoretical calculation

I have a \$1.5\Omega\$ resistor and \$8.84V\$ battery. My multimeter tip's resistance is \$0.3\Omega\$. I've tried to compare the calculated voltage drop (which is \$8.84V\$) with the measured value. What I've tried I've connected the resistor to…
user28936
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Finding the current flowing in parallel circuit

Lets say we have a circuit with a voltage source and a 5 ohm resistor. The voltage source is 20 v and so the current flowing is 4 amperes (according to ohms law). Now, we add a short wire in parallel to the resistor (you can think of it as having a…
vvavepacket
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General definiton of Ohm's law

There has been some disagreement lately on whether a diode follows Ohm's law or not: Does a diode really follow Ohm's Law? Specifically things like However, the truth is the resistance of a diode changes depending on the applied current and or…
Matt
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Finding the voltage of a circuit composed of a series and parallel?

I was watching a youtube tutorial to understand calculations using ohm's law and I thought I had it down when I ran into this problem: I was asked to find the voltage at points A and B. I was also asked to find the current that runs through both…
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