A very long solenoid with a circular cross section and radius r= 7.10 cm with n= 1.50E+4 turns/m has a magnetic energy density uB= 5.10 mJ/m3.
a) What is the current in the solenoid?
b) What is the total energy stored in the solenoid if its length is 0.600 meters? (Neglect end effects.)