The Doppler Effect is also called the Doppler shift; it is a change in the wavelength or frequency of a wave for a viewer who is walking relative to the wave source. The Doppler Effect got its name in 1842 after Christian Doppler a physicist from Austria who discovered the phenomenon.
An example of the Doppler effect would be the variance in the pitch of a train sounding its horn. It will change noticeably from a distance as it approaches and goes by a nearby observer. At this point, the quantity of frequency received is very high.
The Doppler effect occurs as a result of the observer in motion, the source in motion, or the medium in motion.
List of Common Uses for the Doppler Effect:
1. Use in Flow Measurement
Instruments have been developed such as the Acoustic Doppler Velocimeter (ADV) and the laser Doppler velocimeter (LDV) they are used to calculate the velocities in fluid flow. The ADV emits ultrasonic acoustics and the LDV emits a light beam, to help calculate the Doppler shift in the wavelength of reflection from particles in motion with the flow.
2. Use in Vibration Measurement
The Laser Doppler Vibrometer (LDV) is non-contact equipment that is used to measure vibration. The LDV emits a laser beam that is directed to the surface of interest, and as a result, the frequency and the amplitude can be read from the Doppler effect of the laser beam frequency because of movement on the surface.
3. Use in Audio
There are some speakers such as the Leslie speakers which are often associated with and used alongside the famous Hammond organ. It makes good use of the Doppler shift by applying an electric motor to turn an acoustics horn to the surroundings of a loudspeaker, this makes the sound move in circles. The results are in rapid changing frequencies of a keyboard not at the ear of the observer.
4. Use in Velocity Profile Measurement
The ultrasonic Doppler velocimetry (UDV) was originally created to measure velocity in medical applications that is blood flow. The ultrasonic Doppler velocimetry can calculate the complete velocity of must liquids whose particles are in suspension in real-time for example emulsion, dust and gas bubbles, the flows could be turbulent or lamina, pulsating, transient or stationary, oscillating. This method is not all that offensive.
5. Use in Radar
There are radar systems that uses the Doppler effect, to calculate the velocity of target objects. A radar beam is shot at a target in motion for example a vehicle. The police use the radar to detect vehicles that are at high speed, shooting this moving vehicle with the radar beam helps to accurately calculate the velocity of the vehicle and indicated how fast the vehicle is going.
6. Use in Medicine
Doctors can use an echocardiogram, with certain limitations, to produce a precise assessment of the velocity of cardiac tissues and blood and determine in which direction blood flows at any given point with the Doppler effect’s help. One of the drawbacks is not being able to assess the cardiac function and valve areas. Calculating the velocity of blood flow in the veins and arteries using the Doppler effect is an accurate tool to determine vascular issues such as stenosis
7. Use in Military
With the help of sonars, the military uses the Doppler effect to be able to determine the speed of their submarines. The son buoy generates stable frequencies that will experience a Doppler effect when they come in contact with any object in motion or the submarine. The velocity in which the object in motion is reseeding or approaching from the target object is recorded.
8. Use in Aerospace Navigation
As we had earlier discussed radars use the Doppler effect. The aeronautical department uses it too to calculate the speed of flying objects for example drones, planes jets, etc.
9. Use in Astronomy
Astronomy is the study of celestial bodies such as stars, planets, and phenomena that started out of the earth’s atmosphere. Telescopes can be used to see stars and other bodies, but it has its limitations. At certain distances images are not that clear. Hence the speed at which galaxies and stars are coming towards us or moving away from us. It is used to calculate the speed at which galaxies and stars rotate and if a star is in close range (binary).
10. Use in Measuring Speed of an Automobile
The Doppler effect can be used to calculate the speed of any automobile. Calculations of the change of radio waves from rotating satellites, for example, are used in the navigation systems of marine and can also be used in radar surveillance to determine the speed of automobiles.
