The doppler effect
- The Doppler effect is when the there is an observed change in the frequency of a wave, when the observer the source are straight across each other, and occurs when the the object is moving slower than the speed of sound
- To the right is an diagram illustrates a stationary source emitting sound waves. The wavelengths will always be equally spaced apart.
- The Doppler effect is something on is used to witnessing a majority of their lives, fro example when you see police car drive by with its flasher on. When the car is approach you will hear a high pitched V ROOM due to the compression of the waves in front the vehicle, whereas when the car passes you would hear a low pitched V ROOM because the waves are more spaced or have a very low pitch.
- Below is a diagram which shows a police car moving from point A to point B. Someone observing from point B would see the waves at a much higher frequency when the vehicle is moving towards them wheres Someone standing at point A would see the waves at a much lower frequency. When the source is stationary the waves are equally spaced. Someone standing at either side of the waves would hear the sound at the same frequency.
Try it at home with a bicycle and speaker by riding the bike at a high speed and playing a siren on the speaker you would be able to see a mild Doppler effect, we will not be held responsible for any injury try at your own risk.
Sonic Boom
Suppose a object such as a military aircraft was to move at such a speed where it was either equal to or more than the speed of sound, this phenomenon is called sonic Boom. In this case the source will always be on the outermost edge. Notice the circle in the Diagram below the circles are bunched up at the front or with the aircraft this phenomenon is called a Shock wave. In addition, if you are attending a airshow you may see a supersonic aircraft, an aircraft which moves faster than the speed of sound, when the aircraft reaches a certain speed you are able to witness a sonic boom. Sonic boom occur when wave front pile up in front of the object or like the first one in the two down below.