When sufficiently high frequency light hits a metal surface it emits electrons. Now what will happen if the light is coming through two slits and forming an interference pattern similar to the double-slit experiment on the metal surface? Will the metal surface emit electrons or not?
Bright spots in the pattern are where almost all photons hit, dark spots in the pattern are where almost no photons hit. The emission will occur in the bright areas.
In double slit interference the classical explanations implied photons were hitting in the dark areas but cancelling each other out (which is a violation of conservation of energy). The modern understanding is the photon wave function which has highly probable paths (causing bright areas) that the photons follow. A requirement of a the photon path is that its length is a multiple of its wavelength.