1. The problem statement, all variables and given/known data When an aluminum ring is placed on ring launcher so that it surrounds the coil, it flies upward when a AC current is applied to the coil. This does not occur when the intact ring is replaced by a split ring (see below). Explain this in 3 sentences or less. Feel free to use as many diagrams and equations as you need in your explanation. [Warning: The standard explanation of this lacks any mention of an essential feature.] 2. Relevant equations 3. The attempt at a solution This is my rationalization as to why this occurs: When the AC-current was turned on, the emf generated in the Aluminum ring led to a current in it, which according to Lenz's Law, has to be in a direction such that its field cancels the one due to the ring launcher: so it is opposite in direction and since opposite currents repel, the ring flies off. When a split ring is used, since it is not a closed loop, there is no flux going through it is 0. Hence, there is no emf or current generated: so it does not fly off. Did this go beyond the "standard explanation", as my Professor puts it? Or did I miss something "essential?" I have uploaded a picture of the figure (if it helps at all). I can only receive partial credit if my Professor isn't completely satisfied with the answer so if I'm missing something, I would greatly appreciate it if anyone could help steer me in the right direction. Thank you so much!