A circular loop of wire with radius r = 0.0480 m and resistance R = 0.160 Ω is in a region of spatially uniform magnetic field, as shown in Fig. E29.22. The magnetic field is directed out of the plane of the figure. The magnetic field has an initial value of 8.00 T and is decreasing at a rate of dB/dt = -0.680 T/s.

(a) Is the induced current in the loop clockwise or counterclockwise?

Video transcript

Hey, everyone. This problem is working with magnetic fields and currents. Let's see what it's asking us. We have a figure and it depicts a metallic ray placed in a uniform magnetic field that's directed into the plane of the figure. The ring is given we have a given radius in resistance. And we're told that the magnetic field is increasing at a certain rate. We're asked to determine the direction of the current induced in the ring. Our multiple choice answers are a counterclockwise b clockwise, C no current flows or D, none of these a changing magnetic field means that we have continuously changing flux, which we know induces a current into the ring. So as our magnetic field increases our flux increases, we can recall that through lenses law, the direction of the field of current is opposite the direction of the magnetic field. So the magnetic field is going into the page and therefore the current is going out of the page. So we can say the magnetic field is into the page and therefore the field from our current is out of the page. The last step here is the right hand grip rule where we take our right hand, we point our thumb in the direction of the current field. So that's going to be out of the page. And then we see which direction our fingers curve. So with our thumb out of the page, our fingers curve in the counter clockwise direction. And so that is the correct answer to this problem. A that's all we have for this one. We'll see you in the next video.