Why can't you microwave stuff in foil wrappers?

Answer by  suzieQ (21)

A microwave cooks food by radiation. It is like sending radio waves through your food to put energy into the food. Adding energy excites the food particles and heats it up. Metal acts like a mirror and reflects the waves rather than allowing them to penetrate and put energy into it.

Answer by  PedroAlfonsoDoderoEscalante (5)

Foil wrappers (aka aluminium foil, aluminium is a metal) will react with the microwaves and cause sparks. This could lead to a fire, the microwave could be seriously damaged.