Two narrow slits of width a are separated by center-to-center distance d. Suppose that the ratio of d to a is an integer d/a=m. Show that in the diffraction patterns produced by this arrangement of slits, the mth interference maximum (corresponding to dsin(theta)=m[tex]\lambda[/tex]) is suppressed because of coincidence with a diffraction minimum. Show that this is also true for the 2mth, 3mth, etc., interference maxima. My attempt dsin(theta)=m[tex]\lambda[/tex] indicates the conditions for interference maxima, where d is the distance between the two slits. We know that diffraction minimum occurs when a*sin(theta)=[tex]\lambda[/tex], where a is the slit width. Divide by both equations and we can determine which interference maximum coincides with the first diffraction minimum: d/a=m I don't really understand what the question wants. Could someone please help me out? Thanks in advance.