Electromagnetic waves are all around us. This includes not only visible light, but also invisible ultraviolet and infrared rays. Infrared rays, with wavelengths longer than visible light, are also a familiar part of electrical appliances.

Infrared rays with wavelengths of 2,500 nm and less are called near-infrared rays and are used in TV and VCR remote controllers, as well as in fiber-optic communications. Wavelengths above 2,500 nm are called far-infrared rays and are used in heaters and stoves. Ultraviolet rays, with wavelengths shorter than visible light, pack high energy that results in sunburns and faded curtains. Ultraviolet rays with wavelengths of 315 nm and less are particularly dangerous because they destroy the DNA within the cells of living creatures. The bactericidal effect of ultraviolet rays is employed for medical implements, but we also know that large doses of these rays can trigger diseases such as skin cancer and have an impact on the entire ecosystem.