Does Ohm's law apply to AC circuits? I don't understand how it would apply as voltage and current lag . . .

Question

behind one another. Ohm's law states that current and voltage are proportional. So technically AC circuits do not obey Ohm's law, correct? Thanks all.

Answer 1

I = V/Z

Where:
I = Current
V = Voltage
Z = Impedance

To use Ohm's Law in an AC circuit you must calculate the total impedance of the combined RCL components

Answer 2

Yes it does, it depends on whether it is a capacitive, resistive or inductive circuit. It could be combination such as RC, RL, or RLC circuit. Applications of ohms can be used to solve for the current, voltage etc.. when a switch is opened or closed at t=0 where a capacitor is charging or an inductor. The charging occurs in an exponential format so differential equations has to be used in order to solve for these variables in AC circuits. A sin or cosine power source is used instead of just a dc source obviously, this makes the calculations a little more complicated.

Answer 3

If you have a purely resistive circuit, nothing lags. It's completely proportional. Ohm's law works like a champ.

If it is inductive, voltage is before the current.

If it is capacitive, current is before the voltage.

So yeah, with impedences that are not just truly resistive, the dumbed down version of Ohm's law doesn't apply.

ELI the ICE man!!!

Answer 4

Yes it does. If the A.C. signal is driving a pure resistance, then the voltage and current obey Ohm's law for each instantaneous value. If there is a capacitor or inductor involved, Ohm's law is modified to take into account phase shifts caused by the added components. The resistance is replaced by a value called the impedance.

http://en.wikipedia.org/wiki/Ohm's_law

Answer 5

ohm's law says nothing about high voltage creating high current. instead, it describes the relationship between voltage, resistance, and current. the power company delivers a certain amount of "power" over the line. that power stays fixed in a mathematical sense - P is constant, and P = V * I. Let's say for example that 100W was coming into your house. If you get it at 1V, then the current is 100A. The power company may say 100A could fry someone too easily so they step up the voltage to 10000V, but since they're still only delivering 100W, the current would have to be 0.01A.

Answer 6

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To measure the voltage across something, you place a lead on either side of the component. You can then use that value to determine the power that is consumed by that 'thing'. If you measure the voltage across just the wires connecting the components, you will need a very sensitive voltmeter to get a reasonable measurement. These wires may have a voltage relative to the negative terminal of the battery, but there is almost no voltage difference across the wire itself, and THAT is the basis for the power it consumes. Power lines are like that. There is very VERY little voltage drop across power lines. The voltage drop occurs in the appliances and electronic equipment connected to the power lines.

Answer 7

The exact replication of Ohm's Law is the following equation:

(VOLTAGE) = (CURRENT) * (IMPEDANCE)

For purely resistive circuits, the impedance can be simplified to simply "R"; for capacitive and inductive components, the phase angle relationships have to also be taken into account.

The equation is satisified at any instantaneous point, which means you'd have to plug in the correct data for the current waveform to obtain the corresponding voltage waveform.

Answer 8

Ohm's laws applies. At the AC, the loads becomes s-parameters and reactive.

All the voltage divider still applies and current law.

The value of voltage and current has real and imaginative components to it.

Answer 9

AC circuits do in fact obey Ohm's law. V=IR. It works no matter what kind of electrical signal is used. AC, voice, tone or digital signals.

Answer 10

Yes it does obey ohms law.
It's just that its the rms voltage and current.