Interference

• Two waves or pulses in the same place at the same time combine and appear to be a single wave or pulse. The waves continue on unchanged by the interaction in the direction of propagation (i.e. the direction they were traveling).
• Constructive interference happens when the resulting amplitude is larger.
• Destructive interference happens when the resulting amplitude is smaller. In some cases there is Complete Destructive interference where there is no sign of a wave or pulse passing.

 Standing Waves

• Waves interfering with their own reflection in such a way as to appear to be standing still.
• Resonance happens when standing waves form. Small amounts of force applied at the right frequency result in larger and larger vibrations.
• Area of minimum vibration are called nodes. Between the nodes are areas of maximum vibration that are called antinodes.