- #1
*FaerieLight*
- 43
- 0
Hi,
I've seen a couple of posts in the Homework section of Physics Forums about the fields of solenoids, but neither of them seem to address the problem that I have about it. The set-up is a long solenoid that has a sinusoidally varying current going through it. We can establish that the magnetic field outside the solenoid is 0 and inside the solenoid it is varying sinusoidally with the current. The varying B field then sets up a sinusoidally varying E field inside and outside the solenoid. My question is, if there is a varying E field outside the solenoid (which I find to be in the azimuthal direction), shouldn't this induce a B field outside the solenoid as well, by Ampere's Law? If this is so, then we wouldn't have been able to establish the result that B=0, since that result assumes there is no varying E field within an Amperian loop outside the solenoid. Could someone please tell me what is happening here? It appears that Maxwell's equations can't be used in this way, or we arrive at inconsistencies. Or am I making a mistake with my reasoning?
Thanks!
I've seen a couple of posts in the Homework section of Physics Forums about the fields of solenoids, but neither of them seem to address the problem that I have about it. The set-up is a long solenoid that has a sinusoidally varying current going through it. We can establish that the magnetic field outside the solenoid is 0 and inside the solenoid it is varying sinusoidally with the current. The varying B field then sets up a sinusoidally varying E field inside and outside the solenoid. My question is, if there is a varying E field outside the solenoid (which I find to be in the azimuthal direction), shouldn't this induce a B field outside the solenoid as well, by Ampere's Law? If this is so, then we wouldn't have been able to establish the result that B=0, since that result assumes there is no varying E field within an Amperian loop outside the solenoid. Could someone please tell me what is happening here? It appears that Maxwell's equations can't be used in this way, or we arrive at inconsistencies. Or am I making a mistake with my reasoning?
Thanks!