L11= L22 = 3 + 2/3x (mH)

L12 = L21 = 1/3x (mH)

where x is in meters, (a) If i1 = 5 A dc and i2 = 0, what is the mutual electrical force between the coils at x = 0.01 m? ( b ) If i1 = 5 A dc and the second coil is open-circuited and moved in the positive x -direction at a constant speed of 20 m/s, determine the voltage across the second coil at x = 0.01 m.