- #1
Ajoo
- 17
- 0
Hi there.
On my electromagnetism test there was the following question:
A long solenoid with radius R has N turns per unit length and carries a current I = I_0*cos(ωt)
Find the electric field inside and outside the solenoid.
I got the following solutions:
[tex] \vec{E} = \frac{\mu}{2} N I_0 sin( \omega t ) r \vec{e_\theta}, r<R [/tex]
[tex] \vec{E} = \frac{\mu}{2} N I_0 sin( \omega t ) \frac{R^2}{r} \vec{e_\theta}, r>R [/tex]
My professor says the electric field outside the solenoid is zero which makes sense because we used the approximation that the magnetic field outside is also zero.
However i still have some doubts in this.
If i look at the expression of Faraday's Law all i can see is that the absence of magnetic field only implies that the electric field is conservative and the field i calculated seems to be so.
And i still don't get how if i draw a circular line around the solenoid there is magnetic flux going through the surface that line supports while there is no electric field outside.
Can someone please throw some lights on me?
Thank you and forgive me for my english :P
On my electromagnetism test there was the following question:
A long solenoid with radius R has N turns per unit length and carries a current I = I_0*cos(ωt)
Find the electric field inside and outside the solenoid.
I got the following solutions:
[tex] \vec{E} = \frac{\mu}{2} N I_0 sin( \omega t ) r \vec{e_\theta}, r<R [/tex]
[tex] \vec{E} = \frac{\mu}{2} N I_0 sin( \omega t ) \frac{R^2}{r} \vec{e_\theta}, r>R [/tex]
My professor says the electric field outside the solenoid is zero which makes sense because we used the approximation that the magnetic field outside is also zero.
However i still have some doubts in this.
If i look at the expression of Faraday's Law all i can see is that the absence of magnetic field only implies that the electric field is conservative and the field i calculated seems to be so.
And i still don't get how if i draw a circular line around the solenoid there is magnetic flux going through the surface that line supports while there is no electric field outside.
Can someone please throw some lights on me?
Thank you and forgive me for my english :P