1. The problem statement, all variables and given/known data Suppose that you want to design a solenoid to control magnetically the central locking system of your car doors. This needs a magnetic induction at the end of the coil of 0.161 T. To be compact enough to fit next to the window winder mechanism, the coil can be only 3.03 cm long and 0.688 cm in diameter. The car battery can supply 8.23 A. How many turns of wire does the coil need to have if it has air as its core? 2. Relevant equations B = μ0I N / L 3. The attempt at a solution 0.161 = 4π x 10 -7 * 8.23 * N / 0.0303 N = 471.69 turns approximately I don't know how to take into account the information given about the diameter 0.688 cm. How can I adjust the formula to get a more accurate result?