Question

What are the highest – frequency and the lowest – frequency parts of the EM spectrum ?

Answer 1

Normal white light contains a rainbow of colors ranging from red and orange to blue and purple. We can't see a lot of other colors of light. This includes light that is just outside the range of human vision, such as ultraviolet (UV) and infrared (IR).

Complete answer:
The electromagnetic spectrum encompasses electromagnetic waves whose frequencies varying from below $1$ $Hz$ to above ${10^{25}}$ $Hz$, corresponding to wavelengths ranging from thousands of kilometres to a fraction of an atomic nucleus's size. The electromagnetic waves within each frequency band are given different names, and the frequency spectrum is divided into separate bands. The name of the separate bands in the increasing order of their frequencies and decreasing order of their wavelengths are given below:

Radio waves < Microwaves < Infrared < Visible light < Ultraviolet < X-Rays < Gamma Rays

Since, we can see that radio waves are in the starting, hence Radio waves have lowest frequencies, highest wavelength and lowest energy also whereas on the other side Gamma Rays have highest frequencies, lowest wavelength, highest energy. X-rays, gamma rays, and radio waves are the examples of more exotic sources of radiation. The electromagnetic spectrum, or EM spectrum for short, is made up of all of these various colors of light.

Note: A technique known as spectroscopy can be used to physically distinguish waves of different frequencies in most of the frequency bands mentioned above, creating a spectrum that shows the constituent frequencies. Other technical applications are in electromagnetic radiation.