An experimenter performs a Young’s double–slit experiment successively with red light of wavelength λr=700nm and blue light of wavelength λb=450nm. The same pair of slits, separated by 0.30 mm, is used each time, and the screen is placed 1.8 m away from the slits.
(a) Calculate the fringe widths βr and βb for red and blue light respectively.
(b) For each colour, find the distance of the third bright fringe from the central maximum.
(c) By what factor is the spacing between successive bright fringes for red light larger than that for blue light? Comment briefly on your result.