What is a Conducting Loop and What Happens when it is Halfway in the Magnetic Field?

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A conducting loop, often referred to as a solenoid, is an electrical conductor that has coiled wire or tubing that forms a continuous circuit.

When the magnetic field strength is strong enough, the coil will have current flowing through it. This flow of current can cause voltages to appear across each end of the coil. 

The voltage at one end of the coil is opposite in polarity to the voltage at the other end; this creates what’s called ‘eddy currents’. These eddy currents are induced by Lorentz forces which act on electrons within atoms and make them orbit faster around atoms’ nuclei.

Do you know that a conducting loop is halfway into a magnetic field.

The sizes of eddy currents are proportional to the strength of the magnetic flux. Eddy current flow is induced by a change in the magnetic field that opposes and/or counteracts the source of the change. 

Also, as currents increase, they oppose increases in magnetic field strength and thus increase in magnitude when current flows through a coil. 

As a result, eddy currents will flow and attempt to balance out any changes made to the permeability or conductivity of materials (i.e. when an electric current is passed through coils).

Here are some points discussed about Conducting Loop-

1. The current flowing through a coil creates a magnetic field.

It opposes changing magnetic flux by setting up numerous eddy currents within the material that is being changed, and thus, creates a steady-state in which the changes are negligible.

The eddy currents cause electric fields to develop, and as a result, resist changes in permeability. In this way, the circuit acts as an electric motor driving a brake.

The magnetic flux has to be larger than a minimum threshold (B) for a conducting loop to produce eddy currents and thus act as an electric motor driving a brake.

2. Eddy currents are not actually a current. 

Eddy currents are rather flows of electrons which produce and set up a magnetic field. An eddy current is the flow of electrons across and over an electric field, not a current.

The direction of the magnetic flux lines at any cross-section in the coil determines which direction these electrons will flow. The magnetic flux lines easily deflect in such a way that eddy currents remain in their direction unless deflected by another, stronger external field.

3. Eddy currents can generate magnetic fields.

As eddy currents flow they arc in every direction, creating a magnetic field. The magnitude of the field is proportional to the eddy current flux. 

By changing the direction of the eddy current flow, one can create a permanent magnetic field. Eddy currents act as electric motors and brakes within a conductor and are able to withstand changes in permeability and conductivity without being destroyed.

4. An eddy current brake is most efficient at high speeds.

The braking effect of an eddy current is directly proportional to the number of turns, formula_1, and inversely proportional to the speed, formula_2. The torque generated by the motor will be constant as long as all magnetic fields are uniform, i.e., constant field strength (B) and uniform flux (formula_3). 

As flux increases a more important role for the number of loops will emerge. The current through the coil at any given moment is now proportional to the number of loops, formula_4. 

At higher currents, formula_1, an eddy current brake will operate at only a fraction of its maximum braking torque. The efficiency of eddy current brakes therefore drops as increased speed is approached.

5. The use of eddy current brakes as a means of current conversion is widespread.

Eddy currents are used in many applications to convert a direct current into an alternating current, such as in electric motors and generators. 

In this way, eddy currents act as the mechanical brake on a motor or generator, converting energy that would normally be lost in transmission into useful energy products such as electrical power or rotating magnetic fields. 

Similarly, many electrical devices require the addition of an eddy current braking element to provide some amount of braking (e.g., dimming ballast lights) while still allowing the motor resistor to perform its normal function.

The magnetic field created by the current flowing through an electric conductor is at right angles to both the direction of the current and the magnetic field produced from a permanent magnet. Although the term “eddy current” is commonly used, that’s not correct; it should be called “eddy-current”, with a hyphen.


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