A solenoid 25.0 cm long and with a cross-sectional area of 0.500cm2 contains 400 turns of wire and carries a current of 80.0 A. Calculate:
a) the magnetic field in the solenoid;
b) the energy density in the magnetic field if the solenoid is filled with air;
c) the total energy contained in the coil’s magnetic field (assume the field is uniform); d) the inductance of the solenoid.