We-3 The Doppler Effect (with microwaves)
Aim
To demonstrate that a wave reflected from a moving object has its frequency shifted.
Apparatus
- Doppler Alarm unit
- Stereo Amplifier
- Speaker
- Steel Rule
Doppler Shift Burglar Alarm Setup and Diagram.
Description
The Doppler alarm unit sends out a beam of microwaves. The beam reflected from a moving object (flicking a steel rule works well) is Doppler shifted. The original wave and its Doppler shifted wave are fed into a non linear device (a diode) which has as its output a component due to the difference frequency in the audible. This is amplified and clearly heard in a large lecture theatre.