# Electromagnet V vs Amp vs Turns?

Hey guys just a quick question, I understand that to make a stronger electromagnet you need to increase the turns, or voltage or increases wire size for more current.

My question,: to turn a 10 watt DC magnet into say a 20 watt DC which of these in the end would make a stronger magnet:

To simple double the voltage? Or change wire gauge and/or turns?

Just wondering which would have less losses/more power?

power = V x I
V = I x R
magneto-motive force = turns x I.

for constant R, power is portional to V-squared, magnetic field to V.

For most magnetic field and least power you want low R, low V and high I and high turns.
low R and high turns means more copper (which may not be possible due to lack of room
of course).

[ note that with an iron-cored magnet once the iron saturates you have pretty much reached
a limit (in practice, not in theory) ]

My question,: to turn a 10 watt DC magnet into say a 20 watt DC which of these in the end would make a stronger magnet:

To simple double the voltage?

If you double the voltage you get double the current, but Power = V x I so that's 4 times the power (40W). Four times the heat might be an issue...

DVDdoug:
If you double the voltage you get double the current, but Power = V x I so that’s 4 times the power (40W). Four times the heat might be an issue…

So simply increase the voltage by 41% which will increase the current by 41% which will double the power from 10W to 20W. However as mmf (magnetomotive force) is a function of ampere-turns the mmf will only increase. by 41%

If you want double the mmf then you are going to have to double the current (by doubling the voltage)
Providing you are only pulsing the solenoid for relatively short duty cycles then the increase wattage shouldn’t be a problem.

Hey guys just a quick question, I understand that to make a stronger electromagnet you need to increase the turns, or voltage or increases wire size for more current.

My question,: to turn a 10 watt DC magnet into say a 20 watt DC which of these in the end would make a stronger magnet:

To simple double the voltage? Or change wire gauge and/or turns?

Just wondering which would have less losses/more power?

Hello there,

The wire size of any coil is chosen to keep the temperature rise of the wire from going too high and ruining the thin coating on the wire that insulates it from the other turns of the coil when it is wound on a coil form. There are certain guidelines for choosing the wire size but if you have a construction already and you want to change it then you can scale the wire size knowing what it is you want to change.

If you have a magnet that is wound with a certain gauge wire and you know it is rated for a certain current, then if you want to increase that current to 2 times the original level then you usually need to increase the wire cross sectional area to 2 times the original, which means the AWG size has to go down by 3 steps.
So for example if your original coil has #20 AWG wire and you want to double the current, you need to change the wire size to #17 AWG wire. If it had #17 to begin with, then you need to change it to #14 AWG. Of courses that means that if it has #20 to begin with and you wanted 4 times the current you'd have to go down in wire gauge from #20 to #14 AWG.
This assumes that you use the same type of wire with the same type of coating.

Also, when you add turns to a coil you can increase the magnetic strength of the coil, but on the other hand you increase the resistance if you use the same diameter wire. This means that you get less current which decreases the strength of the magnet. That means that if you start with a coil with N turns and AWG wire gauge and double the turns to 2*N then you should decrease the AWG wire size by 3 wire sizes, which will keep the resistance approximately the same, but you'll then have more turns and thus more magnetic strength. You have to be careful not to go too big on the wire size if the power supply can not handle the lower resistance which can cause higher current.