Answer to Question 10

A solenoid has a diameter of 1.5 cm and a length of 5.0 cm. It has 200 turns and core of magnetic material that has a relative permeability of 130. It has a current of 4.5 A flowing in it. Calculate the energy density. State the correct unit. 
The diameter is irrelevant, as area does not come into the equation.
Formula:
U = [4p × 10^{7} H m^{1} × 130 × (200 turns)^{2} × (4.5 A)^{2}] ÷ [2 × (5.0 × 10^{2} m)^{2}] = 2.6 × 10^{4} J m^{3} 