If you have a length (l) of wire coiled to make an inductor and you stretch the wire (ie. space the coils further) but do not change the diameter (see
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) is the inductance the same? I understand inductance to be L = (mu N^2 A) / l + 0.45d. So if I'm stretching the coils but not changing l (length) will the inductance change? I guess that technically the cross sectional area (A) would be changing slightly due to stretching to coils ... but I'm not sure if that minor variation is negligible - since I'm not actually changing the diameter. I thought that you compress/decompress coils (which is what I think this example is) to tune inductance... is this what's happening? How does a variable inductor work? I have no equipment so I can't just coil some wire and stretch it myself to see. Insight is appreciated. Thanks.