Microwave oven consumes less power due to

Microwave ovens consume less power compared to conventional ovens primarily due to the efficiency of dielectric heating. Microwaves operate at a frequency of 2.45 GHz, which corresponds to a short wavelength of approximately 12.2 cm [t1][t6]. This specific short wavelength allows the radiation to be small enough to fit within the oven cavity and efficiently interact with water molecules in food [t4]. Unlike conventional heating, which heats the air and the oven walls, microwaves penetrate the food directly, causing polar molecules like water to rotate and vibrate rapidly [t3][t9]. This direct energy transfer means less energy is wasted heating the surrounding environment, leading to faster cooking times and lower overall power consumption. The development of the cavity magnetron was essential for producing these electromagnetic waves of a small enough wavelength to achieve this localized heating effect [t4].

Sources

1. [1] https://www.sciencedirect.com/topics/chemical-engineering/microwave
2. [2] https://en.wikipedia.org/wiki/Microwave_oven
3. [3] https://www.cfs.gov.hk/english/programme/programme_rafs/files/microwave_ra_e.pdf