radio wave: Light, radio and infrared radiation are forms of energy. This type of radiation takes the form of waves. A huge range of wavelengths has been measured. Radiation with very low energy has a long wavelength, and is called a radio wave. Radio waves can travel long distances. They can transmit electrical impulses through space. So, they are used for telecommunications.
radioactive: Material that gives off harmful radiation is said to be radioactive. Radioactive material can come from a nuclear reaction. Radioactive material also results from the natural decay of certain unstable elements, such as uranium and radon.
