Water Vapor and Ice
Oh, that's why the air inside the microwave oven doesn't get hot!
So ice should heat quickly because solids have high density.
No friction means no heating. But I can microwave a frozen burrito. What gives?
Well, often the microwave oven doesn't heat frozen food well (as there can be frozen spots inside.)
You have to have liquid water for heating to occur.Eventually the outside of the food melts and you
can use that water to heat up the rest of the frozen food. The defrost button is specifically
designed for this purpose.
I always thought that was just a low power setting.
Not quite. It's not just low power. It pulses the microwaves on and off. There is usually some
liquid water at the surface of the ice. The pulse of microwaves heats this water, allowing time for
the heat to spread throughout before more heating is done.