A microwave oven heats food by bombarding it with electromagnetic radiation in the microwaves portion of the electromagnetic spectrum. This causes water molecules in the food to vibrate, producing heat that cooks or defrosts the food. The energy is transferred from the outside of the food inward, so foods cook more evenly in a microwave than they do on a stovetop or in a conventional oven.
The maximum temperature that can be achieved in 30 seconds will depend on several factors, such as:
-The wattage of your microwave
-The type and amount of food you are trying to heat
-The starting temperature of the food
-How much time has elapsed since you started heating it.
In general, however, most microwaves will be able to heat food to between 70 and 90 degrees Celsius (158 and 194 Fahrenheit) in 30 seconds.