Question

Why should we always use glass utensils while microwaving something in the microwave and not in steel utensils?

Answer 1

The answer is complicated: large steel utensils such as bowls can be used, however, the contents will heat more slowly than if the bowl was glass or plastic because the microwaves can't penetrate steel and so can only heat the contents through the open top. Steel utensils such as forks shouldn't be used if their tines are exposed as they are likely to arc (spark) and may melt the tips. On the other hand, a fork buried in the food, such as mashed potatoes is OK - no arcing. But the whole thing gets more complicated.