A microwave oven works by using microwave radiation to heat up food. The oven contains a magnetron, which generates electromagnetic waves in the microwave frequency range (around 2.45 gigahertz). These waves are then directed into the oven cavity.
When the microwaves enter the oven cavity, they interact with the water molecules present in the food. Water molecules are polar, meaning they have a positive and negative end. The alternating electromagnetic field generated by the microwaves causes the water molecules to rapidly align themselves with the field, which results in molecular movement and friction.
This molecular movement and friction generate heat, heating up the food from the inside out. Unlike conventional ovens that heat the food by conduction, where heat gradually transfers from the outside to the inside, microwaves heat the food directly through the excitation of water molecules.
Now, regarding lasers, they can indeed be used to heat up food, but the mechanism is different from microwaves. Lasers work by emitting focused beams of light that carry a lot of energy. When the laser beam interacts with an object, it gets absorbed by the material, which then converts the light energy into heat.
However, using lasers to heat up food for cooking purposes is not common in household settings. Lasers have been used in industrial food processing, such as in certain types of food packaging or for precision cooking applications. But due to the concentrated and potentially hazardous nature of laser beams, they are not practical or safe for general use in heating food at home like microwave ovens. Microwaves remain the preferred method for everyday food heating due to their convenience, efficiency, and safety when used properly.