# Magnetomotive Force (MMF) Definition

Want create site? Find Free WordPress Themes and plugins.

Magnetomotive force is defined as,

“The force produced by current through a coil of wire is called magnetomotive force (mmf), as shown in the following figure. It is the force by which a magnetic field is produced. Just as an increase in electromotive force produces more current in a circuit, so an increase in the mmf increases the strength of the magnetic field.

## Magnetomotive Force (mmf) Unit

Magnetomotive force (mmf), represented by ℑ, is measured in ampere- turs (A-t) of the coil shown above.

“One Ampere-turn is the amount of magnetic force or flux produced when one ampere flows through a single turn of an electrical conductor.”

## Magnetomotive force (MMF) Formula

The magnetomotive force (mmf) formula is expressed by the following relationship.

$\mathfrak{F}=A-t$

A coil having 10 turns and 1A of current produces the same magnetic flux or force as one having 5 turns and 2A current because the ampere-turns are the same.

Example

What is the magnetizing force of a coil having 4000 turns and 10 mA current flowing through it?

Solution

We have following formula to calculate ampere – turns (magnetizing force):

$\mathfrak{F}=A-t$

So, putting values of current and turns into formula,

$\mathfrak{F}=4000*0.01=40A-t$

Thus, if a large amount of magnetizing force is needed and only a small amount of current is available, it is necessary to use a great number of turns on the coil.

You May Also Read:

Magnetic Flux Definition and Unit

Magnetic Flux Density Definition and Unit

Magnetic Flux Intensity Definition and Unit

Did you find apk for android? You can find new Free Android Games and apps.