Microwaves tend to come in 2 types, ones with a rotating plate and ones without. Assuming everything else is equal about a microwave does rotating the food assist with the reheating?
As others have said, microwave ovens create standing waves with regions of higher power (hot spots), which unevenly heat food. If you want to see this for yourself, Scientific American has a kids project for measuring the hot spots in a microwave using chocolate or marshmallows. There’s also a bunch of videos on YouTube of people essentially doing this same project.
As long as you don’t put it in the center, yes.
I had a microwave that moved the plate side to side which worked really well for heating anything solid, but heating liquids usually resulted in a mess.
It makes the heating more even. The microwaves aren’t uniform inside so rotating helps even things out.
Here’s a (trained electrical masters) putting metal in a microwave. I don’t remember if its this or another of his microwave videos in which he warms up the cardboard box and looks at it with a thermal camera.
Or maybe it was a veritasium microwave plasma video where they show it i can’t recall
I had a square one so without a rotating plate, IIRC it was the microwave emitter that rotated instead. If that is plausible, I sort of doubt it a little now.