How Do You Calculate the Magnetic Field and Energy in a Solenoid?

[nissanztt90]

Homework Statement

Consider a solenoid of length L, transverse area A, total number of loops N

Compute the magnetic field B inside the solenoid, assuming that it is uniform and vanishes outside the solenoid, neglect any boundary effects.

Working under the same assumptions, calculate the total energy input necessary to turn on an electric current through the solenoid from 0 to a final value I. This computation must involve an integral.

Homework Equations

I need to derive B = u₀ (N/l) I for the first part.

The Attempt at a Solution

I don't really know where to start, that's really all i need is a starting point. I am a bit confused, so if someone knows which equations to use/or start with that would be a big help.

For example i had another problem where i had to compute the electric field E in a parallel plate capacitor...needed to derive E = Q/($$\epsilon$$₀A), but i had V=Ed, V=Q/C, and C = ($$\epsilon$$₀A)/d to start with.

 

[muppet]

Do you know Ampere's Law?
If so, think about what kind of path you'd need to use for it to be helpful.