A student wants to figure out if an unlabeled item is a capacitor or inductor. He applies a voltage with diferent frequencies and find that as the frequency goes up, the current through the item goes down. Is this a capcitor or an inductor? Why? Thanks for the help! Please explain in detail.
An easy way to remember the answer is to apply DC (frequency 0) and see what happens: In inductor is simply a coil of wire. If DC is applied, it will be nearly a short circuit, and very high current will flow. As the frequency increases, the current will get lower. A capacitor is simply 2 parallel plates that don't touch, separated by a dielectric. If DC is applied, you will have an open circuit and no current will flow. As the frequency increases, the current will also increase.
inductor. Inductive reactance is proportional to frequency, so it goes up as frequency goes up. Since Current is inversely proportional to reactance, as frequency goes up, current goes down. A cap would be the opposite. .
