2
$\begingroup$

In a question:

To construct a solenoid, you wrap insulated wire uniformly around a plastic tube 12cm in diameter and 50cm in length. You would like a 2.2 A current to produce a 2.6 kG magnetic field inside your solenoid.

What is the total length of wire you will need to meet these specifications?

In the provided answer:

$$NC = nL C = (\frac{B}{\mu_0 I}) L (\pi d)$$

Where:

  • $N$ is total number of turns
  • $n$ is number of loops
  • $C$ is circumference

But I dont understand why is there an $L$


I did it by:

$$B = \mu_0 n I$$

Then length of wire needed is just $nC$ whats wrong?

$\endgroup$

1 Answer 1

1
$\begingroup$

$n$ in this case isn't the number of loops, it's the number of loops per unit length. This is why you have to multiply it by $L$ to get $N$.

$\endgroup$
1
  • $\begingroup$ True. Our professor stressed on this point a lot, so that we wouldn't make a mistake. :) $\endgroup$ Jun 25, 2013 at 12:14

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

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