One World Built On A Firm Foundation
Music8 mins ago
No best answer has yet been selected by CaptainSi. Once a best answer has been selected, it will be shown here.
For more on marking an answer as the "Best Answer", please visit our FAQ.They are at either end of the visible spectrum:
http://www.usbyte.com/common/approximate_wavelength.htm
Light has wavelength and frequency. Infra-red light is low frequency, while ultraviolet is high frequency. These frequencies lie outside the range observable by the human eye.
Imagine your eyes are like a radio receiver that can only pick up medium wave (MW) stations. Infra-red would be like long wave (LW), while ultra-violet would be like short wave (SW) or even VHF (FM). You know those other wavebands are there, but you're not able to tune into them with the receiver you've got.