Final answer:
Photons, like electrons, exhibit wave-particle duality and will behave like particles when observed at the slits in a double slit experiment, leading to the collapse of the wave interference pattern.
Step-by-step explanation:
Just like electrons, photons also exhibit a wave-particle duality. When photons pass through a double slit without being observed, they create an interference pattern on the detector, indicative of wave-like behavior. However, if we place detection equipment at the slits to observe which slit a photon passes through, the photons will behave like particles and the interference pattern will disappear, leaving behind two bands similar to particle behavior. The very act of measuring or detecting which path the photon takes results in a change from wave-like to particle-like behavior. This phenomenon is part of the quantum mechanical principle that observation affects the observed, which is significant in experiments involving quantum wave interference. The particles, be they electrons or photons, interfere with themselves to create the characteristic interference pattern when not observed, underscoring the wave aspect of their wave-particle duality.