# What is Inductor (Coil)?

The coil is a circuit element produced by overlapping or side-by-side wrapping of a conductive wire. The unit of the coil is henry (H), and the symbol is L. When ac current is applied to the coil, a magnetic field is formed around the coil, as the direction of the current is constantly changing. Since this magnetic field shows additional resistance to the current, the resistance of the coil to the current increases in AC circuits. In DC circuits, the resistance of the coil to the current is the omic resistance caused only by the metal from which the coil is produced.

## Contrasting Electromotor Force in Coils (EMK)

When AC current is applied to the coil, magnetic fields in different directions around the coil have two effects on the coil. The first effect is that during the increase of the value of the applied AC current from zero to the maximum value, the magnetic field of the coil resists the force that constitutes it and tries to reduce this current. The second effect is that while the AC current value decreases from the maximum to zero, this time it tries to slow the decrease of the current by creating (inducing) tension on the magnetic field itself. During this second effect, the voltage that the coil's magnetic field creates on itself is called the opposite EMK. Coils delay the passage of the current with the opposite EMK, causing AC-enabled currents to lag 90 degrees behind. Factors Affecting Coil Induction: Factors such as the number of windings in the coils, the type of nucleus, the wire section, the range between the windings, the number of winding solids, the shape of the coil, the diameter of the coil, the type of winding and the frequency of the AC current applied are factors that change the value of the induced. Behavior of Coils Against AC and DC Current: When DC current is applied to a coil, an inductive current does not form, only a fixed magnetic field is formed, and substances such as iron, nickel, cobalt that are brought closer to this area are drawn by the coil. Coils without nuclei in them have little gravitational pull. Unlike dc current, when AC current is applied to the coil, an effect occurs that prevents current entanglement due to different magnetic fields formed around the winding. The intensity of resistance, which varies depending on the inductiveness of the coil, is called inductive reassurance.

## Types of Coils

Air nucleus coils Air nucleus coils are usually coils used in high frequency circuits. The induced values of the air nucleus coils connected to the circuit may change even by hand changing position, and this change can negatively affect the operation of the circuit. Therefore, silicone-like substances are coated on the coil in order to protect air nucleus coils from such mechanical effects in some circuits.

## Ferrit nucleus coils

Ferrit nucleus coils are produced by combining nucleus iron, nickel, cobalt, aluminum, copper and some additives. Ferrite nucleus radio frequency coils are usually wrapped in the form of honeycomb winding, which reduces the leakage capacity between the coilspirs. With a small conductor in such nuclei, it is possible to produce coils of the desired value. Nuclei made of brass and aluminum show high force against magnetic force lines, reducing inducation, while ferrite nuclei increase inducation. Iron Nucleus Coils Iron nucleus coils, also known as shock coils, are often used in filtration and sound frequency circuits.

## Nucleus Moving Coils

The magnetic field of the coil and its inducation can be changed by the movement of the nucleus in the moving coils.