What is Induced EMF? Learn its meaning, types, units, and examples of statically and dynamically EMF in generators, transformers, and other devices.
Definition of Induced EMF
When current in a coil changes, the flux changes. The flux links to a coil’s turns. The linking flux to the turns of the coil induces EMF. This EMF is called Induced EMF.
The two types are statically and dynamically induced EMF. It is also called induced voltage,electromotive force, electromagnetic induction, or electromotive force induction.
The more the rate of change of flux, the more the induced voltage.
Unit of Induced EMF
The SI unit of induced EMF is the Volt (V).
In practical circuits, smaller units like millivolt (mV) or microvolt (µV) may also be used depending on the magnitude of the EMF.
1 Volt is defined as the EMF that drives 1 ampere of current through a resistance of 1 ohm.
This EMF can also be expressed as Weber per second (Wb/s), which relates to the rate of change of magnetic flux.
Types of induced EMF
It is possible to induce voltage in two different ways; that is by statically or by dynamically.
STATICALLY INDUCED EMF
Statically induced voltage generates when both coil and magnetic field system are stationary at the same time. The flux links to the coil without physical movement of the coil and magnetic field system. The examples are inductor and transformer.
The change in flux that links to a coil happens due to a change in electric current in the field system.
Read detailed article on: What is Statically Induced EMF? Definition, Formula & Diagram Explained
Categories of Statically Induced EMF
Statically induced voltage occurs when both the coil and magnetic field are stationary. It has two main types:
1. Self-Induced EMF
- Generated within the same coil due to changes in its own magnetic flux.
- Opposes the change in current (Lenz’s Law).
- Example: Inductor smoothing current variations.
Read detailed article on: What is Self Induced EMF? – Definition and Explanation
2. Mutually Induced EMF
- Generated in a secondary coil due to flux changes in a nearby primary coil.
- Magnitude depends on the rate of current change and coil coupling.
- Example: Transformer transferring energy from primary to secondary coil.
Read detailed article on: What is Mutually Induced EMF? definition and explanation
DYNAMICALLY INDUCED EMF
In dynamically induced voltage, if the field is stationary, the conductor is moving, and if the field is moving, the conductor is stationary.
- In a DC generator, usually the coil rotates and the field remains stationary.
- In an AC alternator, usually the field rotates and the coils are stationary.
By following either of the above processes, the conductor cuts across the magnetic field, causing induced voltage in the coil.
Read detailed article on: What is Mutually Induced EMF? definition and explanation
Difference Between Statically and Dynamically Induced EMF
| Feature | Statically Induced EMF | Dynamically Induced EMF |
| Coil and Magnetic Field | Both stationary; flux changes due to current variation | Either coil or magnetic field moves relative to each other |
| Cause of EMF | Change in flux due to change in current in the field system | Conductor cuts across magnetic field lines |
| Examples | Inductor, Transformer | DC Generator, AC Alternator |
| Categories | Self-induced, Mutually induced | Not categorized |
Applications of Induced EMF
The principle of EMF is widely used in electrical devices to convert magnetic energy into electrical energy or to detect and control currents. Some common applications include:
- Generators: Convert mechanical energy into electrical energy. As the conductor rotates in a magnetic field, a voltage is produced, powering homes, industries, and machines.
- Galvanometers: Measure small currents. A voltage generated in the coil by interaction with a magnetic field deflects a needle, allowing precise current measurement.
- Transformers: Transfer electrical energy between circuits. A changing current in the primary coil creates a varying magnetic flux, generating voltage in the secondary coil, enabling voltage to be stepped up or down.
- Motors: Convert electrical energy into mechanical motion. Current-carrying conductors in a magnetic field experience a force, causing rotation. EMF generated in the coils also helps regulate current flow.
- Inductors: Store energy in their magnetic field. Any change in current produces a voltage that opposes the change, aiding in filtering, energy storage, and stabilizing circuits.
FAQs on EMF
Dynamically induced voltage occurs when either the conductor moves in a stationary magnetic field or the magnetic field moves while the conductor is stationary.
This EMF is produced when both the coil and magnetic field system are stationary, and the flux linking the coil changes due to a change in current.
The SI unit of EMF is Volt (V).
It is used in generators, transformers, motors, galvanometers, and inductors.
It is also called induced electromotive force, electromagnetic induction, and electromotive force induction.
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