1. Microwave is used to heat food, while light wave is used for barbecue.

2. Microwave heating of food is both inside and outside, and the time is relatively short. Light waves heat food from outside to inside.

3. The principle of microwave heating is simply that when microwave is radiated to food, food always contains a certain amount of water, and water is composed of polar molecules (the positive and negative charge centers of molecules do not coincide even when the external electric field does not exist), and the orientation of such polar molecules will change with the microwave field. Due to this movement of polar molecules of water in food. As well as the interaction between adjacent molecules, it produces a phenomenon similar to friction, which makes the water temperature rise, so the temperature of food also rises. The food heated by microwave is heated at the same time, so that the whole object is heated evenly and the heating rate is fast. It heats the food 5cm deep at a frequency of 2.45 billion times per second, accelerating the molecular operation.