We divide the electromagnetic spectrum into six major categories of light, listed below. Rank these forms of light from left to
right in order of increasing wavelength. To rank items as equivalent, overlap them.a.gamma raysb.X raysc.ultravioletd.visible lighte.infraredf.radio waves
Notice that these wavelengths span an enormous range. The wavelengths of gamma rays can be smaller than the size of an atomic nucleus, while the wavelengths of radio waves can be many meters (or even milometers) long. Visible light spans only a very narrow range of wavelengths, from about 400 nano meters at the blue (violet) end to about 700 nano meters at the red end.
b) the result we got can be termed approximation because we are neglecting the shear stress acting on the two ends of the cylinder. Here we have considered only the share stress acting on the curved surface area only.