How Do You Calculate Mutual Inductance Between a Wire and a Loop?

Antepolleo
Messages
40
Reaction score
0
It's electromagnetics time again.
I'm horribly stuck on a homework problem. It has to do with mutual inductance, and I know how the problem works conceptually, but I'm having a difficult time with the mathematics. The problem:A very long (read: infinite) wire is a distance d from the center of a conducting circular loop of radius b. Find the mutual inductance between them.

I know, by Ampere's law, the the magnetic flux density of the wire will be
\vec{B}=\frac{\mu_{0}I}{2 \pi r}\hat{a}_{\phi}

With r being the distance from the wire. I know this will cause a magnetic flux to pass through the surface enclosed by the circular loop, and it will not be uniform. I can't for the life of me figure out how to put this in mathematical terms. I'm pretty sure I need to use this:

\phi = \int_{S}\vec{B} \cdot d \vec{s}

But I'm not sure where to put the differential, or even which coordinate system to use.
 
Last edited:
Physics news on Phys.org
how is the loop oriented in relation to the wire?
 
Thread 'Need help understanding this figure on energy levels'
This figure is from "Introduction to Quantum Mechanics" by Griffiths (3rd edition). It is available to download. It is from page 142. I am hoping the usual people on this site will give me a hand understanding what is going on in the figure. After the equation (4.50) it says "It is customary to introduce the principal quantum number, ##n##, which simply orders the allowed energies, starting with 1 for the ground state. (see the figure)" I still don't understand the figure :( Here is...
Thread 'Understanding how to "tack on" the time wiggle factor'
The last problem I posted on QM made it into advanced homework help, that is why I am putting it here. I am sorry for any hassle imposed on the moderators by myself. Part (a) is quite easy. We get $$\sigma_1 = 2\lambda, \mathbf{v}_1 = \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix} \sigma_2 = \lambda, \mathbf{v}_2 = \begin{pmatrix} 1/\sqrt{2} \\ 1/\sqrt{2} \\ 0 \end{pmatrix} \sigma_3 = -\lambda, \mathbf{v}_3 = \begin{pmatrix} 1/\sqrt{2} \\ -1/\sqrt{2} \\ 0 \end{pmatrix} $$ There are two ways...
Back
Top