# Inductance of a circular loop

#### Ramiel

Joined Feb 19, 2018
74
Hello everyone.
I just need some clarification on this question then I will post my attempt. I want to know does it matter that it was a conductor and then bent to a circular loop. Will the answer be the same if the question just started with saying that there is a circular loop of etc?

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#### WBahn

Joined Mar 31, 2012
26,303
Hello everyone.
I just need some clarification on this question then I will post my attempt. I want to know does it matter that it was a conductor and then bent to a circular loop. Will the answer be the same if the question just started with saying that there is a circular loop of etc?
Does it make much since to talk about the electrical inductance of a circular loop made out of glass or some other non-conducting material?

#### crutschow

Joined Mar 14, 2008
25,666

#### RBR1317

Joined Nov 13, 2010
573

#### Ramiel

Joined Feb 19, 2018
74
Does it make much since to talk about the electrical inductance of a circular loop made out of glass or some other non-conducting material?
Oh no I mean does it matter if the question said a circular loop conductor instead of a conductor is bent to a circular loop?will the answer to the question be different

#### Alec_t

Joined Sep 17, 2013
11,745
No, it doesn't matter. A loop is a loop, whether it was moulded, bent, extruded, or otherwise formed into the loop.

#### Ramiel

Joined Feb 19, 2018
74
Okay so i have the formula to solve it as shown in the picture, but i need the derivation, but I dont know how to find the magnetic field intensity to work it.

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#### MrAl

Joined Jun 17, 2014
7,849
Hello everyone.
I just need some clarification on this question then I will post my attempt. I want to know does it matter that it was a conductor and then bent to a circular loop. Will the answer be the same if the question just started with saying that there is a circular loop of etc?
Hi,

You are probably nit picking the question but that just means that you are looking deeper than you need to for this particular kind of question. You might be thinking that since the wire was bent that maybe the homogenity of the cross section of the wire changed such that the density near the inner diameter is now greater than the density near the outer diameter. That would be a very interesting question to pursue, but when we also note that the question also states that the radius of the loop is much greater than the radius of the wire, that means that they are not nit picking much and are willing to treat the diameter of the wire as being insignificant so why would they want to consider variations in cross sectional density. Besides, to handle that case you'd have to find a formula to describe that kind of change and figure out the variation in current density from inner to outer diameters and that would be beyond the likely premise of the question.

So do you have to derive the formula? To do that you have to go back to more basic fundamentals like either Ampere's Law or Biot Savart. In the math the final integration starts at the outer diameter and extends to infinity. I would hope that you have at least worked with a short straight wire first.

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