0
$\begingroup$

I am really not able to understand why is it that the current,while finding the magnetic field in the solenoid (ideal one), is not $I$ the current flowing throught the solenoid but $nI$, where $n$ is the number of turns per unit length.

p.s:Using Amperian loop.

$\endgroup$
1
$\begingroup$

Because thats the current going through the integration area: enter image description here

More info on Ampére's law: http://en.wikipedia.org/wiki/Amp%C3%A8re%27s_circuital_law

$\endgroup$
0
$\begingroup$

i'm assuming you're looking for an intuition. here it is. let us say that the width of the wire in 1 cm, you'll get 100 turns per 1 meter. let us look at the central axis inside the solenoid, and the magnetic field on it. look at a 1 mm wide patch. approximately only 1mm wide ring of wire with current in it will contribute to the magnetic field of this patch. so the field is going to be: $B\times 1mm\sim total current per 1 meter \times 1 mm=100\times I\times 1mm$, hence $B=100\times I$.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.