# Do Resistors work the same on AC voltage?? Answered

This isn't for a project but I'm interested if resistors still work the same: Wattage, Resistance...
Thanks :)

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The formulas are the same. Basically you can just substitute RMS values for {voltage, current, power} in place of values for constant or instantaneous

{voltage, current, power}.

Supposing Ohm's law, for DC, is

V = R*I

and P = V*I = R*I^2 = V^2/R

where V, I, P, are constant in time, or constant over an arbitrarily small interval in time (i.e instantaneous).

Substitute in RMS values, and it turns out, these equations are still valid,

Vrms = R*Irms

and Prms = Vrms*Irms = R*Irms^2 = Vrms^2/R

It's the same formulas, but the meaning is a little different, since now we're talking about RMS values, instead of constant or instantaneous ones.

Yes. Assuming a standard carbon or composite resistor and low frequency AC. There will be minor issues and they can be worked around by working the AC as a RMS (root mean squared) value.

A resistor dissipates power as heat and it will do that just as well for AC as DC.

Things get funny at high frequency but that is more the nature of high frequency signals rather than the resistor.