['Radio Waves: Instant Communication. ••• Radio waves are the lowest-frequency waves in the EM spectrum. ... ', 'Microwaves: Data and Heat. ••• ... ', 'Infrared Waves: Invisible Heat. ••• ... ', 'Visible Light Rays. ••• ... ', 'Ultraviolet Waves: Energetic Light. ••• ... ', 'X-rays: Penetrating Radiation. ••• ... ', 'Gamma Rays: Nuclear Energy. •••']