# Help to make a solenoid/Electromagnet.

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1. Jun 7, 2015

### Shahryar

I need to make an electromagnet with maximum 20mm dia including winding.
I have an iron core of 10mm dia and 20mm length.

I can't decide
- which wire to choose,
- what no. of turns should i provide
- how much current should i pass through the wire.
- what should be the voltage.

Any help and advice will be highly appreciated.
Thank you

2. Jun 7, 2015

### Hesch

Don't think of N and I separately. Think of N*I = some constant, which induces a constant magnetic induction ( B-field with the unit [Tesla] ).
How many Tesla do you want? ( I will suggest 1 - 1,2 Tesla max. ).
Make some sketch of the cross section of the magnet: The area of the coil must be kept within your given limits: 20mm dia * 20mm length.
Calculate the length of the wire. Knowing the cross section area of the wire you can calculate the resistance of the wire.
V = R * I

The rest: Will the magnet be switched on constantly or on/off ( how much mean-power will it consume, what will its temperature be? ).