Start typing, then use the up and down arrows to select an option from the list. ## Physics

Learn the toughest concepts covered in Physics with step-by-step video tutorials and practice problems by world-class tutors

31. Alternating Current

# Resistors in AC Circuits

1
concept

## Resistors in AC Circuits 3m
Play a video:
Hey, guys, in this video, we're going to start talking about resistors in a sea circuits. All right, let's get to it. Just a reminder in an a C circuit, the current produced by the source is always going to look like this. Okay, it's always going to be signed the soil. All right, Now, because of that, OEMs law tells us that the voltage across the resistor at a sorry as a function of time has to be this current as a function of time, times the resistance, right? If we had a basic circuit exactly is above the voltage across the resistor as a function of time would just be equal to the current traveling through it as a function of time. Times are the resistance. This means that the voltage across the resistor is i Max times are cosine of omega T that it's simply plugging in this equation into homes law. Very basic. Let's do an example. A 10 ohm resistor is plugged into an outlet within arm's voltage of 120 volts. What is the maximum current in the circuit? What about the arms current? Okay, we know that the RMS voltage is 120 volts. Now, just like we could say that the maximum current is equal to the maximum voltage over our. It turns out that the RMS current is also equal to the RMS voltage divided by our. This is something that's really easy to show, and you guys can convince that yourselves of that on your own. So this is 120 volts, divided by 10 owns, which is 12 aunts. Now what's the maximum current? Well, the maximum current is just going to be the square root of two times the RMS current. So that's the square to to times 12 amps, which is about 17 ants. Okay, resistors and a C circuits are very, very simple problems. Alright, now for multiple resistors in an A C circuit. What if you had something like this, for instance, all we have to do is combine them into a single equivalent resistor, as we would with D C circuits. And then we can apply the same equations as we did in the previous example to thes circuits that have multiple resistors. Nothing changes from D C circuits. All right, guys, this was a little bit of a start with resistors in a sea circuits, and we'll get to more of that soon. Thanks for watching
2
Problem

The voltage across a resistor is found to be given by v (t) = (10 V) cos[(120 s−1)t]:

a) At what frequency does the AC course operate?

b) If the resistance is 12 Ω, what is the maximum current in this circuit?

c) What is the RMS voltage of the AC source?

3
example

## Resistors in Parallel in an AC Circuit 2m
Play a video: 