When a strip of magnetic material, variably magnetized, is embedded in a plastic card that is moved past a small coil of wire, what happens in the coil. What is a practical application of this? I have no idea what this means, I don't understand Physics and my teacher doesn't help either. He actually makes it worse, so most of the time I am lost..I am not asking for much I just need someone to explain what this means and possibly get me going in the right direction for an answer!! Thanks!