•Converts mechanical energy into electrical energy- Dynamo
•Compares intensity of colors- Colorimeter
•Measures the frequency of electromagnetic waves- Ondometer
•To see objects above sea level- Periscope
•To determine rotational speed of shafts- Tachometer
•Non-Mechanical waves or Electromagnetic waves:
1.Short radio waves or Hertzian Waves- H. Hertz
2.Long Radio Waves- Marconi
3.Infra-red rays- Hershel
4.Visible radiation- Newton
•The Doppler effect (or the Doppler shift) is the change in frequency or wavelength of a wave for an observer who is moving relative to the wave source.
•Applications of Doppler’s Effect
•To measure the velocities of planets.
•Overspeeding of vehicles.
•To guide the aircraft.