Solenoid 30cm long and 8cm in diameter

[Lindz779]

You have a 12 volt car battery and a supply of #18 gauge copper wire. If you make a solenoid 30cm long and 8cm in diameter, winding two layers of wire along the length of the solenoid, what will be the strength of the magnetic field at teh center of teh solenoid when connected to the car battery? #18 gauge wire has a diameter of 1.02mm.

B=(mu_0*N*I)/L i have B=((4pi*10^7Tm/A)*(294.11turns)*(I))/(.3m) the resistance of copper is 1.7*10^-8 but I am not sure how to get from the 12 volts to the current (I) i have worked this problem a few different ways and i haven't come up with anything that works please help me out

 

[whozum]

You can find the current just by relating the voltage to the resistance, usually the resistance of a material is given per unit length.. is that the case?

 

[Lindz779]

answer

i believe i can do that i found a new formula I=(density*Length)/area * volts and when i worked the problem it came out to be something about 3740T.