9-17-2013 Homework: Dual wave/particle.

Scientists believed for the longest time that light was emitted as either a wave or particle. One theory was that light was wave-like in nature, producing energy that traverses through space in a manner similar to the ripples spreading across the surface of a still pond after being disrupted by a dropped rock. The opposite theory insists that light is composed of a steady stream of particles, much like tiny droplets of water sprayed from a hose. However, both theories hold true in certain circumstances. Under certain conditions, such as when light is shined through narrow slits, it behaves as only a wave can. Under other conditions, such as when light is shined on a metal and the spray of electrons that comes off, light behaves only as particles can.