# Help with Faraday's law of magnetic induction

#### hotepmichael

Joined Jul 6, 2009
1
I am trying to calculate the induced EMF in a coil. I have a flywheel spining at 3600rpms. One revolution takes .01666 sec. One quarter revolution takes .00414 sec.

I am using a flux density calculator on a website Magnetsales.com. It is confusing me because it says I can use whatever system of units I want but it does not ask for inches, cm. When I type in numbers I get a gauss but I'm not confident of the value.

From 0 to total flux only takes .00414 sec. The EMF values I'm getting are in the millions of volts.

Can anybody tell me what I am doing wrong?

Can anybody steer to an online flux density calculator?

Will appreciate any help.

HotepMichael

#### steveb

Joined Jul 3, 2008
2,436
I am trying to calculate the induced EMF in a coil. I have a flywheel spining at 3600rpms. One revolution takes .01666 sec. One quarter revolution takes .00414 sec.

I am using a flux density calculator on a website Magnetsales.com. It is confusing me because it says I can use whatever system of units I want but it does not ask for inches, cm. When I type in numbers I get a gauss but I'm not confident of the value.

From 0 to total flux only takes .00414 sec. The EMF values I'm getting are in the millions of volts.

Can anybody tell me what I am doing wrong?

Can anybody steer to an online flux density calculator?

Will appreciate any help.

HotepMichael
I took a look at their calculators. I believe what they mean by "any distance units can be used" is that whatever units you use for the dimensions of the magnet needs to be the same as the distance you want to know the flux for. So, if you specify the dimensions of the magnet in cm, then you must use cm when you specify the distance you want to know the flux for.

I'm guessing that your voltage is so high because you are using Gauss units instead of Tesla units in your calculations. If you do calculations in SI units, which is typically done, then you need to use Tesla. Note that 1 Tesla equals 10,000 Gauss.

#### aliensong

Joined May 13, 2009
7
I'm guessing that your voltage is so high because you are using Gauss units instead of Tesla units in your calculations. If you do calculations in SI units, which is typically done, then you need to use Tesla. Note that 1 Tesla equals 10,000 Gauss.

I agree with this point.