In Young's double slit experiment, what would happen if we would close one of the slits?
If we would close one of the slits in Young's double slit experiment, the superposition between the two different trajectories would disappear. Therefore, the interference pattern will disappear.
Interestingly, if the hole is very tiny, different wave trajectories through the same hole will be in superposition, and they will interfere with each other. The interference pattern is completely different however, with one big central lobe and smaller side lobes on the screen.