Understanding coils and solenoids

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Is there any place where I can learn how coils and magnets work I have search google and here but still doesn’t answer my questions.
I made a coil with a lot of fine wire and it showed up as 1.1 ohms so I recoiled it with a bit over double the size wire and less coils and it was 1.2ohms so I rewind the coil around a ferrite bar and still 1.2 ohm how does that work? Any formulas?

also I wanted to make a solenoid too
Any help would be greatly appreciated
 
I believe you are having resistance measurement issues, not coil ones. How are you measuring the resistance?


The dc resistance will follow the guage..#12 will be about 1.7 milliohms per foot, #14 at 2.73, #16 at 4.36, #18 at 6.92, 20 at 10.9, 22 at 17.5..Belden has a good chart.

Cheers, John
 
Just touch the meter probe tips together (with no coil in sight!)

It should read zero, but it won't!

You will see the resistance of the meter leads plus the contact resistance of the probes. Easily 1 ohm for a cheapy meter, and hard to get a consistent reading.

Measuring resistance below 1 ohm with any degree of accuracy and consistentency is not easy!
 
Thanks for the info
I’m not sure on the brand of the meter but it’s a fairly good one that you can download some information form the meter to a computer via an optical cable after you have analyzed a component its wasn’t cheap either about 2 years old.
How do speaker get like 500ohms and greater I ran a magnet down the center and didn’t change impedance much anyway I’ll study those links you gave me that may answer my questions.
 
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