To identify the part of the electromagnetic spectrum
For writing its frequency range
Microwaves
Frequency range is 1010 to 1012‌Hz
OR
Production of EM waves:
Electromagnetic waves consist of both electric and magnetic fields travelling through empty space with the speed of light c. These waves oscillate in perpendicular planes with respect to each other and are in phase. An electromagnetic wave can be created by accelerating charges; moving charges back and forth, producing oscillating electric and magnetic fields. When the accelerating charged particle moves with acceleration, both magnetic and electric fields change continuously which lead to production of electromagnetic waves.