Inductance of Copper Wire

[rahul.6sept]

Dear all,

Can anyone let me know what will be effect in self inductance in case of a piece of copper wire (considering hypothetically) whose radius changes when current flows through it ?


Regards,
rc

 

[erikl]

Here you can calculate and see yourself.

 

[rahul.6sept]

Hi erikl, In the paper "The self and mutual inductance of copper wire", by Edward Rosa, there are some approximations taken while deriving self inductance of copper wire.

These approximations may lead to errors and deviation from actual values of L.


regards

 

[FvM]

there are some approximations taken while deriving self inductance of copper wire.

These approximations may lead to errors and deviation from actual values of L.

Not only approximations. There are implicite assumptions about the conductor geometry that don't necessarily apply to the problem you want to analyze.

If you ask me about the inductance of a piece of wire in general, I would answer that it's undefined as long as you don't specify the return path. The problem has been solved in the said approximations in a specific way.

Alternatively, you can refer to a well-defined conductor geometry that has a non-approximative solution for the inductance (if you decide to ignore the frequency and material dependent inner inductance term), e.g. a coxial transmission line.

Or perform a numerical solution of biot-savart's law for your actual geometry.

By the way, I wonder if the words "whose radius changes when current flows through it" really mean what they seem to say?

 

[rahul.6sept]

Hi FvM,

Although "change of radius when current flows" is a idea which is quite a thought experiment for me and m just toying with the idea, would like to see simulating the same and i'd like to include your idea of coaxial transmission line which seems valid idea to me.

Thanks and regards,
rahul