consider a series RLC circuit in which R is an incandescent lamp, C is some fixed capacitor, and L is a variable inductance. the source is 240 volts AC. Explain why the lamp glows brightly for some values of L and does not glow at all for other values???

cheers

 

Inductors and capacitors in the right combination will allow more current to pass through them in what is called "resonance". Let's take an example of a .001 farad capacitor, in a 60hz series circuit, and find what inductor will allow the bulb to go brightest. L=1/(39.5*60*60*.001)=.00703 or about 7mH. If you move the variable inductor away from the 7mH value in either direction, the bulb will go dimmer.