Here's why:

* Electromagnetic Spectrum: Both UV and IR radiation are part of the electromagnetic spectrum, which encompasses all types of electromagnetic waves, arranged in order of increasing frequency and energy.

* Frequency and Energy: Frequency and energy are directly proportional. Higher frequencies correspond to higher energies.

* UV vs. IR: UV radiation lies on the higher frequency (and higher energy) end of the visible spectrum, while IR radiation is on the lower frequency (and lower energy) end.

To summarize:

* UV radiation: Higher frequency, higher energy

* IR radiation: Lower frequency, lower energy