I'm assuming that you're referring to a microwave oven in the kitchen.
-- electrical energy, which it takes from the wall outlet and uses to do its job
-- radio waves, in the form of microwaves at 2.45 GHz, with which it fills the chamber in which the cold meatloaf is placed to warm
-- heat (thermal) energy, which develops inside the food, when meatloaf molecules resonate with the 2.45 GHz microwaves
-- BONUS: visible light energy, if there's a little light bulb inside to let you see the meatloaf as it warms up
