[填空题]
Light of wavelength 680 nm falls on twua n)5wd filqx+(.7yfo sl/jqi ,l +mq4tqrmu. :lits and produces an interference pattern in which the fourth-order fringe is 38 mm from the qq.u/:rllqj+mti , 4m central fringe on a screen 2.0 m away. What is the separation of the two slits? mm
