# inductance value on a 0 ohm coil

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#### siongboon

Will there be still inductance on a coil which the wire is a perfect 0 ohm?

Thanks.
Siong Boon

Yes, it will be the same.

Large superconducting coils with zero resistance and a large inductance are commonly built for laboratory experiments.

Hi godfreyl, crutschow,

The inductance changes with the coil diameter, core permeability, no. of turns, wire diameter.

Why it is that increasing the wire diameter can reduce the inductance, while the rest of the parameter remains the same?
Thanks.

Yes, it will be the same.

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Why it is that increasing the wire diameter can reduce the inductance, while the rest of the parameter remains the same?
If the number of turns and everything else remains the same, then the wire diameter has little effect on the inductance.

The overall length of the coil is increase as the result of increase wire diameter.
Shouldn't the inductance increase?

If the number of turns and everything else remains the same, then the wire diameter has little effect on the inductance.

The overall length of the coil is increase as the result of increase wire diameter.
Shouldn't the inductance increase?
You apparently missed to specify the problem clearly. A dimensional change will affect inductance. But that hasn't been your original question.

Technically, unless you are talking about superconductional inductors, the initial question is absurd.

I was referring to my 2nd question which was posted after godfreyl and crutschow replied with the answer for my initial question.
It was a clear answer then that 0ohm wire will still have inductance.

The 2nd question was,
The inductance changes with the coil diameter, core permeability, no. of turns, wire diameter.
If all the parameters remains the same...
Why it is that increasing the wire diameter can reduce the inductance?

I was assuming that resistance has a simple relation with inductance.
The formula does not suggest so. So I am asking around for the reason for the reduce in inductance after the wire diameter is increased.
Or maybe I am in a wrong direction?

Siong Boon

You apparently missed to specify the problem clearly. A dimensional change will affect inductance. But that hasn't been your original question.

Technically, unless you are talking about superconductional inductors, the initial question is absurd.

The inductance changes with the coil diameter, core permeability, no. of turns, wire diameter.
The inductance is mostly determined by coil diameter, coil length and no. of turns. The wire diameter has only a small effect on inductance.

....................................
The 2nd question was,
The inductance changes with the coil diameter, core permeability, no. of turns, wire diameter.
If all the parameters remains the same...
Why it is that increasing the wire diameter can reduce the inductance?

I was assuming that resistance has a simple relation with inductance.
................
An increase in wire diameter will reduce the inductance if it reduces the number of turns you can wind in the same area. If the turns aren't changed and the core diameter and length aren't changed, then a change in wire diameter will have little effect on inductance.

There is no direct relation between resistance and inductance, other than the resistance is related to wire size and the number of turns that can be placed in a given volume.

inductance is not relative relation with DCR, relation with turns and core AL value.

Hi crutschow,

I was referring to this website, **broken link removed**
When I key in a larger wire diameter value, the computation shows a drop in inductance.
Number of turns remains the same.
The change in inductance is small, and I am expecting a slight increase in inductance,
since the length of the coil increases when the wire diameter increase.

Is there any thing I missed out.

Thank you.

An increase in wire diameter will reduce the inductance if it reduces the number of turns you can wind in the same area. If the turns aren't changed and the core diameter and length aren't changed, then a change in wire diameter will have little effect on inductance.

There is no direct relation between resistance and inductance, other than the resistance is related to wire size and the number of turns that can be placed in a given volume.

The change in inductance is small, and I am expecting a slight increase in inductance,
since the length of the coil increases when the wire diameter increase.

The wire length surely doesn't increase because coil diamater refers to the wire center line (as ususal). A small inductance decrease with increasing wire diameter will be particularly observed with single turn coils, but it can be seen with any kind of air coils.

I was referring to this website, **broken link removed**

.....since the length of the coil increases when the wire diameter increase.
OK, I see the source of the confusion.
The calculator on that website assumes there is no space between the turns, so coil length = wire diameter * number of turns.

For example, 10 turns of 2mm diameter wire gives a 2cm long coil. However what's important when calculating inductance is the coil length, not the wire diameter. If you made a coil of the same diameter with 10 turns of 1mm diameter wire, and stretched it out to 2cm length, it would have the same inductance.

So the calculator's a bit misleading. It uses something unimportant (wire diameter) to calculate something important (coil length), but doesn't explain the assumptions.

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