Answer the following:
(a) Name the EM waves which are used for the treatment of certain forms of cancer. Write their frequency range.
(b) Welders wear special glass goggles while working. Why?

(a) Gamma rays are used for the treatment of certain forms of cancer. The frequency range is 3×1019 Hz to 5×1024 Hz
(b) Welders wear special glass goggles while working so that they can protect their eyes from harmful electromagnetic (UV) radiation
(c) Infrared waves are often called as heat waves because they induced resonance in molecules and increase internal energy in a substance. Infrared waves are used in burglar alarms, security lights and remote controls for television and DVD players.