[" 58.The frequency of a light wave in a material is "2times10^(14)],[" Hz and wavelength is "5000" A.The refractive index of "],[" material will be "],[[" (a) "1.50," (b) "3.00],[" (c) "1.33," (d) "1.40],[" 59.A microscope is focussed on a mark on a piece of paper "]]