# Simple Magnetic Field Increase/Decrease question.

by Metalsonic75
Tags: field, increase or decrease, magnetic, simple
 P: 436 Simple Magnetic Field Increase/Decrease question. Ok, you've made some good observations but let's be very clear about what's going on here. There is a current I in the wire loop. This is an induced current caused by the applied magnetic field. The applied magnetic field changes with respect to time (we know this by Faraday's Law). We want to know if this magnetic field is changing positively or negatively, that is, is $$\Delta B$$ positive or negative. Lenz's Law tells us that the induced magnetic field, that is, the magnetic field caused by the induced current, will act to oppose the change in the applied magnetic field. You've already mentioned that the induced magnetic field points out of the page inside the loop, so which direction must the change in the applied magnetic field point? And subsequently, does this constitute an increase or decrease in the applied field?