how to test inductance of wire

[466576266]

hello, can someone tell us how to test the inductance of wire.
the length of the wire is about 0.5m, and i have a LCR meter.please tell me test the inductance of the wire step-by-step,especially how to set the LCR meter.
thank u in advance.

---------- Post added at 03:57 ---------- Previous post was at 03:56 ----------

just forget: the cross section of the wire is 50mm.

 

[FvM]

Inductance is a property of conductor loops. Definition and measurement both require a current return path.

 

[466576266]

Inductance is a property of conductor loops. Definition and measurement both require a current return path.

hello, FvM, see u again here.
u mean it cannt test the inductance of a wire which donnt have a current return path?
but what is LCR meter for, i think it can test resistance, capacitance and inductance accurately.
but i just donnt know how to set the value of the LCR meter, such as frequency and so on.

 

[mister_rf]

In generally we need to associate inductance with a loop or coil of wire. However, even a straight piece of wire has some self-inductance. That’ s more easy to calculate, but difficult to measure without bending the wires. :grin:

The equation for an isolated round wire far from a ground plane or earth.
L=2 l [2.303 log (4 l/d) – l +µ/4 + (d/2 l)]

L is the inductance in nH (10-9 henry)
l is the length
d is the diameter of the wire (in cm)
µ is the permeability of the material (=1.0, except for iron and other ferromagnetic materials).

 

[466576266]

In generally we need to associate inductance with a loop or coil of wire. However, even a straight piece of wire has some self-inductance. That’ s more easy to calculate, but difficult to measure without bending the wires. :grin:

The equation for an isolated round wire far from a ground plane or earth.
L=2 l [2.303 log (4 l/d) – l +µ/4 + (d/2 l)]

L is the inductance in nH (10-9 henry)
l is the length
d is the diameter of the wire (in cm)
µ is the permeability of the material (=1.0, except for iron and other ferromagnetic materials).

ok, what about the inductance of a length of 0.5m straight wire which is 50mm, i mean, µH level or nH level, 10µH,100µH, or 10nH, 100nH and so on.

from ur equation, we can get that:
cause s equals to 50mm, so the diameter is :d=s√[(4s)/3.14], and the length I equals to 0.5m.
so we can get the inductance of the wire. am i right? thank u.

 

[mister_rf]

So d= 7.978 mm
L = 478.21nH

 

[FvM]

I referred to conductor loops to clarify, that you need to think about which quantity you are actually looking for and how the setup should be.

Regarding instrument parameters, you can expect an inductance roughly > 1 µH with a distant return path, so it should be measurable. Check the manual of your instrument.

The equation for an isolated round wire far from a ground plane or earth.

I wonder, if somebody is able to explain the physical meaning of this value in terms of electromagnetical theory? There's in fact a quantity called inner inductance of a conductor that can be assigned to a straight wire, but it's a rather small part of total inductance.

 

[466576266]

I referred to conductor loops to clarify, that you need to think about which quantity you are actually looking for and how the setup should be.

Regarding instrument parameters, you can expect an inductance roughly > 1 µH with a distant return path, so it should be measurable. Check the manual of your instrument.


I wonder, if somebody is able to explain the physical meaning of this value in terms of electromagnetical theory? There's in fact a quantity called inner inductance of a conductor that can be assigned to a straight wire, but it's a rather small part of total inductance.

the less inductance of the wire, the better for my experiment.

 

[mister_rf]

The whole issue about wire inductance needs a lot more clarification, see details here:
G3YNH info: Components and Materials: Part 2.

 

[466576266]

The whole issue about wire inductance needs a lot more clarification, see details here:
G3YNH info: Components and Materials: Part 2.

wow, detailed explaination about the inductance of straight wire. thank u .

 

[FvM]

Thanks for providing the literature.

I didn't study the derivation very thoroughly, but as far as I understand, the author shows, that the straight wire inductance value is literally valid for a segment of a very large circular loop as a border case. The inductance per length unit value seems to converge against a constant for large loop radii. Presuming the derivation is correct, this solves in fact the problem of defining a return path. The setup is however considerably different from ususal "real world" measurement problems, I think.