# Electromagnet, tesla equations

1. Feb 14, 2004

### billtodd

I know that an electro magnet can have a higher tesla rating when you increase the current or the times revolved around the core but I was wondering if someone could give me an equation or set of equations involving the lenght of wire, gauge of wire, current, cross sectional area of the wire, wire resistance, number of windings and the diameter of the core and the windings. In terms of teslas just plain and simple. For example to achieve 10^-2 teslas what variables would I need to know. Equations or websites would be great, I cant seem to find exactly what I'm looking for.

thanks very very much

billtodd

2. Feb 14, 2004

### Integral

Staff Emeritus
For a solenoid we have:

$$B= \mu_0 i_0 n$$
where:
$$\mu_0$$ is the Permeability of free space. and
$$i_0 =$$ current
n is turns per meter
If you wrap on a metal core, use the permeability of that metal instead of free space.

Notice that most of your requested parameters do not enter into the equation. The properties of the wire will determine the total resistance which will determine the voltage required to achieve the desired current.

3. Feb 14, 2004

### billtodd

permeability?

Notice that most of your requested parameters do not enter into the equation. The properties of the wire will determine the total resistance which will determine the voltage required to achieve the desired current.

do you mean I need the relative magnetic permeability of a material?

4. Feb 14, 2004

### Integral

Staff Emeritus
If you want a meaningful estimate of Magnetic field strength you will need to know the magnetic properties of your core material.