Constructive Interferance occurs when waves come together so that they are in the same point with each other. This means that their movement at a given point are in the same direction, due to the result of the amplitude at that point being much larger than the amplitude of an individual wave. As the waves meet, the amplitude between wave to the crest becomes much larger. For two waves of equal amplitude interfering together, the resulting amplitude is twice as large as the amplitude of an individual wave. After the collision, the wave came back to the original point. In conclusion, due to the constructive interferance, we were able to find a significant increase in amplitude.
When two waves interfere together, they have the same amplitude in opposite directions, But then, there are more than two waves interfering. The situation gets a little more complicated. When the two waves meet in this following example, the collide and go apart as crests and troughs. When the two amplitude have opposite signs, they will also form a wave with a lower amplitude. The following diagram shows two pulses interfering destructively. Again, they move away from the point where they combine as if they never met each other.
When we try to listen to music on an airplane, problem might occur. Headphones that block out the noise and let you enjoy to your music are called noise cancelling headphones. The shape of the headphones and the material they are made of can physically block certain sound waves from reaching your ears. As we learned in this lesson, if the soundwave is 180 degrees, it means that the wavelenght is zero, which result in silence.