. Two long, parallel wires are separated by a distance of 0.400 m (Fig. E28.29). The currents I1 and I2 have the directions shown. (a) Calculate the magnitude of the force exerted by each wire on a 1.20-m length of the other. Is the force attractive or repulsive?

Video transcript

Welcome back everybody. We are given that we have two long electric lines that are suspended vertically. And I'm actually going to label this one on the right line one and this one on the left line to now, we are told for line one we have a current that is flowing downward of 2. amps. And we are told for line two that we have a current flowing upward and the value of that is 3.2 amps. The distance between the two lines is eight cm or .08 m. And we are tasked with finding two different things. We are tasked with finding one. What is the magnitude of force when we are observing a 0.5 m strip of length of this system right here and then B. Is this force going to be attractive or repulsive. So let's go ahead and start with part one here. The formula for the strength of the force is going to be mu not which is just a constant times the current of line one times the current of line two times the strip of length that we are observing divided by two pi divided times the distance between them. So let's go ahead and plug in all of our values Here we have mu naught is equal to four pi times 10 to the negative seventh. We have our current of line one to be two point to our current of line to to be 3.2 and we have the length for the strip of length that we're observing to be 0.5 m. This of course is divided by two pi times r distance between our two wires, which is 20.8 m, which when you plug all of this into your calculator, we get a magnitude of force of 8.8 times 10 to the negative six newtons. Now is this force for part two, a attractive force or a repulsive force? Well, if you'll notice here in line one, we said that the current was flowing downward and for line to the current was flowing upward, since they are traveling in opposite directions, we are going to have that this force is a repulsive force in this system. So not only did we find the magnitude of force, but we found that it was repulsive, which corresponds to our final answer. Choice of B. Thank you all so much for watching Hope This video helped. We will see you all in the next one.