I'm creating an electromagnet (several, actually) to test a hall effect switch. I understand that more wire wraps (turns) increases the magnetic B-field, as does more electric current. Adding more turns of course increases the resistance because there is more wire. I can specify the voltage and change wire gauge to accommodate whatever current is needed, so I have some flexibility.
My questions are, for a given length of core (ferrite rod):
- Do the wraps need to be fairly uniform and consistent, or are small gaps of little consequence?
- How do 2+ layers of wire affect performance? I assume that as layers are added and radius from core center increases, the effectiveness of those layers diminishes. Is this correct, and is there a "rule of thumb" as to how many layers I should consider a maximum?