Electric Field and Inductor

Electric Field 

The electric field is the region around the electric charge and it exerts a force on the electric charge inside the field. It is produced by an electric charge or time-varying magnetic field. The electric field is the reason for the attractive force between the atomic nucleus and the electrons and the forces between atoms that causes chemical bonding. 

The electric field is defined as the electric force per unit charge and its SI unit is Volt/metre (V/m). It is a vector quantity. The direction of the force is the direction of the force acting on the unit charge. The electric field is directed radially outwards for positive charge and directed inwards for a negative charge. The force between two charges is given by Coulomb’s law. The force per unit charge gives the value of the electric field.


The Inductor is a passive component which is also called a coil, choke or a reactor. It has a wire wound into a coil around the core. When there is a change in the current flowing through the coil the time-varying magnetic field induces an electromotive force in the conductor given by Faraday’s law of induction. 


The inductor is described by its nature of inductance. Inductance is the ratio of change in voltage to the rate of change in current. The inductance depends on factors like the shape of the coil, the number of turns of the coil, the space between the turns, permeability of the core material and the size of the core. The inductance of the coil is measured in henry(H).

Power in an Inductor

As per Lenz’s Law, in a circuit, inductor opposes the current’s flow through the circuit as the current’s flow induces an opposing emf. In such a scenario, an external battery source has to do work to keep the current flowing against the induced emf. The power used to force the current against the self-induced emf (VL) is given as 

VL(t) = -L(di/dt)

Power in a circuit is given by P= VI

P = VI = -L(di/dt) x i

An ideal inductor will have the only inductance without any resistance and therefore power is not in the coil, so it has no power loss.

Difference between Inductor and Capacitor

In a capacitor, the energy is stored in the form of electrical energy and in an inductor, the energy is stored as magnetic energy.  The capacitor resists a change in voltage while inductor resists a change in current. The inductor acts as a short circuit for direct current and capacitor acts as a short circuit for alternate current. The smallest inductor is much bigger than the smallest capacitor because the coiled wires in inductor take more space than the thin plates in the capacitor. 

Types of Inductors

The typical types of inductors are

  1. Moulded Power inductors
  2. Multilayer inductors
  3. RF inductors
  4. Coupled Inductors
  5. Surface mount inductors
  6. Chokes

Uses of Inductors

  1. Inductors are used in AC applications like radio, TV etc.
  2. The main use of an inductor is to convert AC supply to DC supply in power supply circuits.
  3. It can be united to form transformers if they have a distributing magnetic lane.


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