>>3492447 (lb)
You can microwave a spoon, but not a fork. The reason is the vibration it causes in the tines on the fork creates arcs. In a spoon, it just runs around in a circuit.
>>3492529 (lb)
Microwaves use electricity and covert the energy into, you guessed it, Microwaves. These waves agitate water molecules in your food to vibrate rapidly, causing heat. If you toss too much juice at something, too quickly, it hits the most moist parts first, and the rest stays cool.
If you want to use a microwave, set the power to 70%, and heat longer (but not by much). You'll find that it heats more evenly/safely.