The electromagnetic spectrum is a range of all possible frequencies of electromagnetic radiation. This spectrum includes different types of waves such as radio waves, microwaves, infrared radiation, visible light, ultraviolet light, X-rays, and gamma rays. Each type of wave has a specific range of frequencies and wavelengths.
The parts of the electromagnetic spectrum that you cannot see are ultraviolet light, X-rays, and gamma rays. These types of radiation have frequencies higher than visible light, making them invisible to the human eye. However, even though we cannot see them, they play important roles in various applications like medical imaging (X-rays), sterilization (ultraviolet light), and cancer treatment (gamma rays).
In summary, the electromagnetic spectrum encompasses a wide range of frequencies of electromagnetic radiation, including visible and invisible parts like ultraviolet light, X-rays, and gamma rays.