7.3 Interference and its Types
Superposition of two waves having the same frequency and travelling in the same direction results in phenomenon called interference.
An experimental setup to observe interference effect of sound waves is shown in Fig. 7.5(a). Two loud speakers and act as two sources of harmonic sound waves of a fixed frequency produced by an Audio Generator (AG). Since the two speakers are driven from the same generator, therefore, they vibrate in phase. Such sources of waves are called coherent sources. A microphone attached to a sensitive Cathode Ray Oscilloscope (CRO) acts as a detector of sound waves. The CRO is a device to display the input signal into waveform on its screen. The microphone is placed at various points, turn by turn, in front of the loud speakers as shown in Fig. 7.5(b).