Conversation so far:
what are the different applications of the em radiation
EM waves are used to transmit TV or telephone or wireless signals and energies. They are responsible for the transmission of energy.
what types of em radiation are there
Radio waves, infrared rays, visible light, ultraviolet rays, X-rays, and gamma rays are all types of electromagnetic radiation.
what are em waves made of
All EM waves are made up of photons that travel through space until they interact with matter; some waves are absorbed and others are reflected.
which is the lowest-frequency wave in the EM spectrum
Radio waves are the lowest-frequency waves in the EM spectrum.

Question: which is the second lowest-frequency wave
Self-contained rewrite: which is the second lowest-frequency wave in the EM spectrum