RAS question
What type of electromagnetic radiation is used in a microwave oven?
Correct answer: (A) Microwave radiation.
A microwave oven uses microwave radiation to heat food.
Explanation
Microwave radiation is the specific electromagnetic radiation used in a microwave oven. Its operating frequency is 2.45 GHz, and its heating mechanism is dielectric heating: microwaves make water molecules in food vibrate rapidly, producing heat. The U.S. Environmental Protection Agency notes the same core idea: microwave ovens use electromagnetic waves that penetrate food, cause some molecules to vibrate, and generate heat that is then transferred through the food. This is why option A is the precise answer. Microwaves are produced only while the oven operates, are absorbed by food, and microwave ovens are constructed so that the electromagnetic radiation does not leave the oven.
Why the other options are wrong
- (B) Radio waves is not the precise exam answer because the oven uses microwaves, not the broader label given in this option.
- (C) Ultraviolet radiation is not supported because microwave ovens use microwaves to vibrate molecules and heat food.
- (D) Infrared radiation is wrong because the heating described here comes from microwaves penetrating food and causing molecular vibration, not from infrared radiation.
Concept
This tests the Science and Technology concept of the electromagnetic spectrum and everyday applications of non-ionising radiation. It recurs in RAS because basic physics is often asked through familiar devices such as ovens, communication systems and medical equipment.