Wok and electric hob - which ring to use? I've a flat electric hob (the gets-very-hot type, not induction) upon which I cook.

When using my wok (which is flat-bottomed) I place it on the largest ring, but obviously the pan only covers a relatively small potion of the ring. I hadn't really thought about it, but for some reason yesterday I was cooking away and it dawned on me maybe the smaller rings would work better.

Do the larger rings normally produce more thermal energy, or the same amount just more spread out?
Would it be better to use the ring that is about the same size as the base of the pan?
The larger ring will transmit more energy, but spread over the size of the ring; so the density is probably roughly the same.

So using an element bigger than your pot/wok bottom is basically just a waste of heat/energy.



Some supporting evidence added by DMA57361:

I've recently gotten a free energy monitor, which tells me the current power consumption of my entire home. So, with a bit of experimentation, I have worked out the approximate power output of each ring on my hob, and this backs up that they have approximately the same output density.

Position     |  Diameter  |  Area   |  Power  |  Density
             |   cm       |   cm²   |   kW    |   kW/cm²
-------------+------------+---------+---------+-----------
Back-Left    |   18       |  254.5  |  1.90   |  7.46
Back-Right   |   16       |  201.0  |  1.45   |  7.19
Front-Left   |   14       |  154.0  |  1.25   |  8.11
Front-Right  |   18       |  254.5  |  1.84   |  7.24