Because of this property, this voltage is called “back electromotive force” (“back emf”). The faster rates of current change always produce a greater back voltage. For example, when the current is increasing, the voltage tends to oppose this increase and to maintain a smaller current and when the current is decreasing, the voltage tends to oppose this decrease and to maintain a higher current. The polarity of this induced voltage is always such that the voltage is trying to maintain the changing current at its present state. They create a voltage drop directly proportional to the rate of change in current through them.

Unlike resistors that simply oppose the electric current through them by creating a voltage, which is directly proportional to the current, inductors oppose changes in the current flowing through them. Inductors resist only AC or changing current and this ability to resist current is directly proportional to their inherent property called inductance, which is denoted with the symbol L in honor of a Russian physicist Emil Lenz and measured in henries named after an American scientist Joseph Henry. Unlike capacitors, which do not pass a DC current, inductors easily pass it through them. Unlike capacitors, which oppose the rate of change of voltage across their plates, inductors oppose the rate of change of current flowing through them. Inductors are widely used in tuned circuits of radio transmitters and receivers and in transformers.Īn air core high Q inductor in a radio transmitter One of the applications of inductors is filters used to remove ripple from the direct current output or to prevent radio frequency (RF) interference from being transmitted through cables. However, unlike in capacitors, the energy in inductors is stored in the magnetic field surrounding the inductor. Like capacitors, inductors are used to store energy. A magnetic core is usually made of a ferromagnetic metal, for example, iron or ferromagnetic ceramic (ferrite), and is used to increase the magnetic field and thus to increase the inductance of the coil. Inductors are also called coils and chokes. To calculate, enter the inductance and the frequency, select the units of measurements and the result will be shown in ohms.Īn inductor is a two-terminal passive electrical component consisting basically of an insulated wire wound around a magnetic core or without it (air core) in the form of a coil. Ω = 2πf is the angular frequency in rad/s,

Z L is the inductor’s impedance in ohms (Ω),

X L is the inductor’s reactance in ohms (Ω), The following formula is used for calculation: However, they are not identical because of the phase shift between voltage and current in an inductive circuit. Note that the magnitude of the impedance of an ideal inductor is equal to its reactance.

4. air core inductor calculator v105