有關微波爐的疑問

Q: 微波爐的微波的穿透力有多強？
Micowave used in household microwave oven is of frequency about 2.4 GHz. The microwave is readily absorvbed by water. Hence, its penetration depends on how much water is there present in the food.

Q: 為何微波爐本身的金屬不會引起火花？
The metallic lining inside the oven chamber, being flat without any sharp points, could not cocnentrate the electric field of the microwave. Thus no spark is produced. Instead, the flat metalic lining acts like a "mirror" and reflects microwave back into the chamber, thus producing a more or less uniform microwave intensity inside the chamber. This serves an advantage that the food to be cooked is heated uniformly by microwave on all sides.

Q: 微波能像光波那樣被聚焦嗎？
Yes, using specially designed devices. The "dish antenna" that you see for receiving satellite signals (for TV or other communication) is a device for focusing microwave from satellites.