Electromagnetic rays covering a range from the limit of the visible spectrum (the near region), wavelengths 0. 75 - 2. 5 gm to the shortest microwaves (the far region) wavelengths 30 - 1000 μm. All warm bodies radiate infrared rays
H. J. Porter (Chairman - Technical Committee), Dictionary of Fire Technology, The Institution of Fire Engineers, The Victory Press (Leicester) Ltd. 1979 UK. (Fr Tech - Brit) {81}