An inductor (or reactor or coil) is a passive two-terminal electrical component used to store energy in a magnetic field. An inductor\'s ability to store magnetic energy is measured by its inductance, in units of henries. Any conductor has inductance (see \"Straight wire conductor\" equation below) although the conductor is typically wound in loops to reinforce the magnetic field.
A linear resistor is a linear, passive two-terminal electrical component that implements electrical resistance as a circuit element. The current through a resistor is in direct proportion to the voltage across the resistor\'s terminals. Thus, the ratio of the voltage applied across a resistor\'s terminals to the intensity of current through the circuit is called resistance. This relation is represented by Ohm\'s law: I = {V \\over R}
A capacitor (formerly known as condenser) is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric (insulator). Capacitors are used as parts of electrical systems, for example, consist of metal foils separated by a layer of insulating film.