Inductive coupling

# Inductive coupling

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Encyclopedia
In electrical engineering
Electrical engineering
Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics and electromagnetism. The field first became an identifiable occupation in the late nineteenth century after commercialization of the electric telegraph and electrical...

, two conductors are referred to as mutual-inductively coupled or magnetically coupled when they are configured such that change in current flow through one wire induces
Faraday's law of induction
Faraday's law of induction dates from the 1830s, and is a basic law of electromagnetism relating to the operating principles of transformers, inductors, and many types of electrical motors and generators...

a voltage across the ends of the other wire through electromagnetic induction
Electromagnetic induction
Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....

. The amount of inductive coupling between two conductors is measured by their mutual inductance.

The coupling between two wires can be increased by winding them into coils and placing them close together on a common axis, so the magnetic field of one coil passes through the other coil. The two coils may be physically contained in a single unit, as in the primary and secondary sides of a transformer, or may be separated. Coupling may be intentional or unintentional.

Unintentional coupling is called cross-talk, and is a form of electromagnetic interference
Electromagnetic interference
Electromagnetic interference is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit...

. Inductive coupling favors low frequency energy sources. High frequency energy sources generally use capacitive coupling
Capacitive coupling
In electronics, capacitive coupling is the transfer of energy within an electrical network by means of the capacitance between circuit nodes. This coupling can have an intentional or accidental effect...

.

An inductively coupled transponder
Transponder
In telecommunication, the term transponder has the following meanings:...

comprises an electronic data carrying device, usually a single microchip, and a large coil that functions as an antenna. Inductively coupled transponders are almost always operated passively.

## Uses

Devices that use inductive coupling include:
• Transformer
Transformer
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductorsâ€”the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...

s
• Electric motor
Electric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...

s and generators
Electrical generator
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...

• Induction loop
Induction loop
Induction loop is a term used to describe an electromagnetic communication- and detection system, relying on the fact that a moving magnet will induce an electrical current in a nearby conducting wire. Induction loops are used for transmission and reception of communication signals, or for...

communication systems
• Metal detectors
• Graphics tablet
Graphics tablet
A graphics tablet is a computer input device that enables a user to hand-draw images and graphics, similar to the way a person draws images with a pencil and paper. These tablets may also be used to capture data or handwritten signatures...

• Radio Frequency Identification
Radio Frequency Identification
Radio-frequency identification is a technology that uses radio waves to transfer data from an electronic tag, called RFID tag or label, attached to an object, through a reader for the purpose of identifying and tracking the object. Some RFID tags can be read from several meters away and beyond the...

• Electronic article surveillance
Electronic article surveillance
Electronic article surveillance is a technological method for preventing shoplifting from retail stores or pilferage of books from libraries. Special tags are fixed to merchandise or books. These tags are removed or deactivated by the clerks when the item is properly bought or checked out...

tags to prevent theft (most types).
• Inductive Modems
• Resonant energy transfer
Resonant energy transfer
Resonant energy transfer may refer to:*FĂ¶rster resonance energy transfer*Resonant inductive coupling...

• Inductive charging
Inductive charging
Inductive charging uses an electromagnetic field to transfer energy between two objects. This is usually done with a charging station. Energy is sent through inductive coupling to an electrical device, which then can use that energy to charge batteries....

products charge batteries using inductive coupling, such as eCoupled
Ecoupled
eCoupled is a proprietary near-field wireless energy transfer technology developed by Fulton Innovation, a division of Alticor. It provides wireless power transfer via inductive coupling between a primary transmission coil and a secondary receiving coil...

; Torches, Cochlear Implants and many electric toothbrush
Electric toothbrush
An electric toothbrush is a toothbrush that uses electric power supplied usually by a battery to move the brush head rapidly, either oscillating side to side, or rotation-oscillation .- History :...

es.
• Induction cooker
Induction cooker
An induction cooker uses induction heating for cooking. Unlike other forms of cooking, heat is generated directly in the pot or pan , as opposed to being generated in the stovetop by electrical coils or burning gas...

s and induction heating
Induction heating
Induction heating is the process of heating an electrically conducting object by electromagnetic induction, where eddy currents are generated within the metal and resistance leads to Joule heating of the metal...

systems

## Low frequency induction

Low frequency induction is an unwanted form of inductive coupling, which can occur when a metallic pipeline
Pipeline transport
Pipeline transport is the transportation of goods through a pipe. Most commonly, liquids and gases are sent, but pneumatic tubes that transport solid capsules using compressed air are also used....

is installed parallel to a high-voltage power line. The pipeline, which is a conductor, and is insulated from the earth by its protective coating, can develop voltages which are hazardous to personnel operating valves or otherwise contacting the pipeline.