# What happen if DC current passes through a coil ?

When direct current (DC) passes through a coil, it creates a magnetic field around the coil according to the right-hand rule of electromagnetism. The magnetic field strength is proportional to the amount of current flowing through the coil and the number of turns of wire in the coil. This phenomenon is fundamental to the operation of electromagnets used in various applications such as electric motors, relays, and solenoids. The direction of the magnetic field depends on the direction of current flow through the coil and can be used to attract or repel magnetic materials or to perform mechanical work.

Passing DC through a coil causes the coil to generate a steady magnetic field as long as the current flows. The strength of this magnetic field is directly related to the amount of current passing through the coil and the physical dimensions of the coil itself. This magnetic field can be utilized in numerous applications, including inductors in electronic circuits where energy storage or filtering is required. It’s also integral to devices like transformers, where coils play a crucial role in converting voltage levels in power distribution and transmission systems.

When current is passed through a coil, the coil generates a magnetic field around itself. This magnetic field is proportional to the amount of current flowing through the coil and the number of turns of wire in the coil. The direction of the magnetic field follows the right-hand rule, where the fingers of the right hand curl in the direction of current flow through the coil, and the thumb points in the direction of the generated magnetic field. This principle underlies the operation of electromagnets and inductors, which are essential components in electrical and electronic systems for tasks ranging from switching operations in relays to energy storage in power supplies.

When the DC current flowing through a coil is switched off, the magnetic field around the coil collapses. According to Faraday’s Law of Electromagnetic Induction, a change in magnetic flux through a coil induces a voltage (or electromotive force, EMF) in the coil. When the current is interrupted or switched off, the collapsing magnetic field induces a voltage in the coil that can generate a brief surge of current, known as a back electromotive force (back EMF). This back EMF can potentially cause voltage spikes in the circuit, which must be managed with appropriate protective devices like diodes or snubber circuits to prevent damage to electronic components.

When DC current passes through an inductor, the inductor resists changes in current flow due to its inherent property known as inductance. Initially, when DC is applied, the inductor allows current to flow smoothly. However, if there is a sudden change in the applied DC voltage or if the current is abruptly switched off, the inductor opposes the change by inducing a voltage (back EMF) that opposes the initial change in current. This behavior is described by Lenz’s Law, which states that the induced EMF will always oppose the change in magnetic flux that produced it. Inductors are used in circuits to store energy temporarily and to control the rate of change of current, such as in DC-DC converters, filters, and energy storage applications.