2- Place all the letters that apply next to the expressions relating the single slit virililth= a: and the wavelength of the light incident on the slit= h . assh a~.i't a}}h a. The raj.r approximation is no longer valid [light is also wave like)- In. The primary effect of the opening is to act like a point source of waves. c. The primary effect of the opening is minimal; light travels in a straight line through it. 1:21. The primary effect of the opening is to di'i'act the light