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The problem I am struggling with is this

You are designing an electromagnet capable of producing a magnetic induction field of 1 T

by winding a solenoid around a long cylinder. A solenoid is typically wound by starting

at one end of the cylinder and placing loop after loop directly next to each other. Once

the other end of the cylinder is reached the first winding layer of the solenoid is complete

and the next layer is started by again placing loop after loop next to each other. You are

using [itex]300 \mu m[/itex] diameter wire and the current needed to reach 1 T should not exceed 10 A.

What is the minimum number of winding layers required?

So I start with this equation

[itex]B=\mu \frac{N}{l} I[/itex]

It seems that there is information missing in the question, such as the material of the wire and the material of the core so I suppose I should just choose which as it doesn't matter really as they will just be values which can be plugged in later. From the information in the question I am guessing I need to use the diameter of the wire to find the length [itex]l[/itex] of the solenoid. I think the length of the solenoid is the number of loops multiplied by the diameter of the wire, [itex]N[/itex] x [itex]d=l[/itex] but substituting this into the Ampere's law gives

[itex]B=\mu \frac{1}{d} I[/itex]

I'm not sure that I've gone the right way here as in this expression there isn't anything I don't know. I've tried using the expression for resistance of a wire which includes the length of the wire and the area but since I only have the current in the Ampere's law expression using the resistance expression will introduce a voltage which I have not been given, eg

[itex]R=\frac{\rho L}{A}=\frac{4 \rho L}{\pi d^2}[/itex]

Then substituting this in to ampere's law[itex]B=\mu \frac{N}{l} \frac{V \pi d^2}{4 \rho L}[/itex]

Getting the voltage in my expression doesn't seem to help my cause much so I am out of ideas. Any help with how I could proceed or where I may be going wrong would be greatly appreciated.