A solenoid of 2100 turn consists of a cross-sectional area equivalent to 8.0 cm2 and a length equivalent to 30 cm. The solenoid carries a current of around 4.0 A.
(i) Compute the magnetic energy stored in the solenoid by using U = 1/2 LI2, where L = µ0n2A.
(ii) Divide your answer in part (i) by the volume of the area within the solenoid to determine the magnetic energy per unit volume in the solenoid.
(iii) Verify your Part (ii) result by calculating the magnetic energy density from um = B2/(2µ0) where B = µ0nI.