A very long solenoid with a circular cross section and radius r= 8.10 cm with n= 1.10E+4 turns/m has a magnetic energy density u B = 6.00 mJ/m 3 .

A very long solenoid with a circular cross section and radius r= 8.10 cm with n= 1.10E+4 turns/m has a magnetic energy density uB= 6.00 mJ/m3. What is the current in the solenoid? What is the total energy stored in the solenoid if its length is 0.660 meters? (Neglect end effects.)