Charles, that is an interesting experiment, but it doesn’t answer Wally’s question, as you are not comparing apples to apples as the saying goes.
Here is a direct quote form Wikipedia, “Induction cooking heats a cooking vessel by magnetic induction, instead of by thermal conduction from a flame, or an electrical heating element”.
Since ceramic electric heats by thermal conduction the affect of the ‘fire ring’ is not the same as heating by magnetic induction. I don’t use ceramic electric stovetops, I only use induction cooking units or propane, so I can’t answer Wally’s question either. Hopefully someone that uses ceramic electric stovetops will provide a definite answer.
Cheers!!... Eldon