What is the optimal gauge wire to use?

Question

I'm building an electromagnet using regular 1.2 volt duracell batteries (4 of them)...together they could last 50 wires. What gauge wire should I use?

Answer 1

You need a heavy enough wire guage to handle the maximum current. If the batteries are connected in parallel, your maximum current is less than the rated current for one battery. If the batteries are connected in series, the maximum current is less than four times the rated current for one battery. Are you using AAA cells or D cells? Are they NiCad or NiMH?

If you use many windings of very thin wire, the current will be a lot less than the the battery rating, and the batteries will last much longer. So, do you want to run the batteries down in seconds or hours?

A tight coil heats up much more than a straight wire, so you you have to either provide a cooling system or use a much heavier guage than what is shown in the tables for ordinary wiring.

You need to give a lot more info about the curcuit and its purpose if want a simple answer.  

Answer 2

Optimize what?  Time the batteries last?  Strength of magnetic field?  Waste heat minimized?  You need to be a whole bunch more specific.

-Fred