1. The problem statement, all variables and given/known data A solenoid 10.0 cm in diameter and 77.2 cm long is made from copper wire of diameter 0.100 cm, with very thin insulation. The wire is wound onto a cardboard tube in a single layer, with adjacent turns touching each other. What power must be delivered to the solenoid if it is to produce a field of 8.00 mT at its center? 2. Relevant equations Alright, I know B=μnI , I=B/μn n=N/L R=ρl/A l=2πr(N) A=π*radius(wire)^2 and P=I2R 3. The attempt at a solution I've gotten all these equations, but just cant put them together >_< n=N/L=772/.772=1000 turns per length I=B/μn = 8e-3/(μ*1000) = 6.3662A now just for R, R=ρl/A l=2πrN = 2(3.1415)(.05)(772) = 242.53 A=π*radius(wire)^2= (3.1415)(.0005)^2 = 7.854e-7 R=(1.7e-8*0.314159)/(7.854e-7) = 5.25 So, P = RI^2 = 5.25*6.3662^2 = 212.77W !!