Transcript: Resonance is a phenomenon that’s common to all vibrations and waves. It’s a situation where a vibration, a wave, or an oscillation caused by one object induces a vibration, a wave, or an oscillation in another object. Obvious example of resonance is the fact that soldiers must break step when they walk across a bridge in case the pattern of their marching motion corresponds to a natural frequency of the bridge, in which case the marching adds energy to the bridge motion which amplifies it into a wave that could destroy the bridge. A better example is pushing a child on a swing. Assume you walk up to a swing where a child is swinging. If you then push the swing with random intervals you will on average loose energy from the swing and the swing will stop. If, however you wait until the swing is just moving forward or every second forward motion or every third or forth or fifth forward motion you will add energy to the swing. This is a resonance. At a fixed period interval, adding energy to the system will increase the original motion. You can see this also occurring with a bell or a tuning fork. If the bell is struck or the tuning fork is struck a similar bell or tuning fork some distance away will resonate.