What are Ampere-turns and Ampere turns per meter?

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In summary, ampere-turns is a unit used to measure the strength of an electromagnet, calculated by multiplying the number of turns in the coil by the current in amperes. Ampere-turns per meter is the measurement of this unit per length of the coil.
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jearls74
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1
could someone please explain in simple terms what ampere-turns and ampere turns per meter means?
 
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  • #2
jearls74 said:
could someone please explain in simple terms what ampere-turns and ampere turns per meter means?

Electromagnetism:

It has been found that an electric current sets up a magnetic field
similar to that produced by a permanent magnet. This action is known as
Electromagnetism and is very important in many devices. A desirable
feature of electromagnetism is that it is possible to control the strength
and polarity of the magnetic field. When current exists in a coil, the coil
has all the magnetic qualities of a permanent magnet and is called an
Electromagnet. If this electromagnet is brought near a permanent
magnet or another electromagnet, the like and unlike poles react exactly
as explained for the permanent magnets. Moreover, an increase of current
in the coil increases the strength of the magnetic field, and a decrease
of current weakens the field.

Ampere-Turns:

When the number of loops or turns of the coil is increased and the
current remains the same, the strength of the magnetic field increases.
Each loop or turn of the coil sets up it's own magnetic field, which unites
with the fields of the other loops to produce the field around the entire
coil. The more loops, the more magnetic fields unite and reinforce each other
and, as a result, the total magnetic field becomes stronger.

To compare the magnetic strength of different coils, and to obtain
a basis for measuring the magnetomotive force of an electromagnet, the number
of turns of wire is multiplied by the number of amperes of current carried
by the wire and the result is called Ampere-Turns (NI). The ampere-turn
is the unit for measuring the magnetomotive force of a current-carrying
coil. In a formula, the magnetomotive force in ampere-turns can be expressed
as:
F = NI
F = magnetomotive force in ampere-turns
N = number of turns
I = current in amperes
For example:
A coil with 10 turns and a current of 10 amperes has an F of 100
ampere-turns.

The above excerpted from: http://ourworld.compuserve.com/homepages/boyce_smith/magnets.htm

Ampere-turns per meter is just as it reads, the number of ampere turns per length of the electromagnetic coil.

Chris
 
  • #3
very good explanation

thanks chris, that explained it very clearly
 
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1. What are Ampere-turns and how are they calculated?

Ampere-turns are a unit used to measure the magnetomotive force (MMF) or magnetic field intensity of a magnetic circuit. They are calculated by multiplying the number of turns in a coil by the current flowing through it, measured in Amperes.

2. What is the purpose of using Ampere-turns in magnetism?

Ampere-turns are used to quantify the strength of a magnetic field and its ability to magnetize materials or attract/repel other magnets. They are also used in the design and analysis of electromagnetic devices.

3. How do Ampere-turns affect the strength of a magnetic field?

The higher the number of Ampere-turns, the stronger the magnetic field will be. This is because the more turns in a coil or the higher the current, the greater the magnetomotive force and therefore, the greater the magnetic field intensity.

4. Can you give an example of Ampere-turns in action?

One example is an electromagnet, where the number of turns in the coil and the current flowing through it determine the strength of the magnetic field it produces. Increasing or decreasing the Ampere-turns can change the strength of the electromagnet's magnetic field.

5. How do Ampere-turns relate to other units used in magnetism?

Ampere-turns can be converted to other units such as magnetic flux density (tesla) and magnetic field strength (ampere per meter) using the permeability of the material in the magnetic circuit. They are also related to the magnetic field strength by the equation H = N x I, where H is the magnetic field strength, N is the number of turns, and I is the current in Amperes.

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