Two circular current loops lie parallel to the x–y plane and are separated by a short distance along z (Fig. P21.28). The currents through these loops are positive if they are counterclockwise as viewed from the +z direction and are negative if they are clockwise.
(a) If the current I₁ through the bottom loop is increasing with time, what is the direction of the induced current in the top loop?
(b) If the current I₂ through the top loop is decreasing with time, what is the direction of the induced current in the bottom loop?

Figure P21.28