In such a resonant circuit where it is in series resonance, the current will be maximum and offering minimum impedance. In parallel resonant circuits the opposite is true. I have known electronic enthusiasts who still couldn't even mentally visualise the concept of impedance even after 25 years. Impedance Diodes Diodes are semiconductor devices which might be described as passing current in one direction only. The latter part of that statement applies equally to vacuum tube diodes.
Diodes however are far more versatile devices than that.
They are extremely versatile in fact. Diodes Transistors Generally transistors fall into the category of bipolar transistor, either the more common NPN transistors or the less common PNP transistor types. There is a further type known as a FET transistor which is an inherently high input impedance transistor with behaviour somewhat comparable to valves. Modern FET's include some very rugged transistor devices. The name transformers is derived from the fact that when two coils are placed in close inductive proximity to one another the lines of force from one cut across the the turns of the other inducing an ac current, energy is transformed from one winding to another and this is called transformer action.