interference

Conditions for interference Sound waves Light waves Young’s double slit experiment

Conditions for interference

All waves exhibit interference Constrictive Destructive For Interference:

The sources must be coherent. The sources should be monochromatic

Sound waves

Sound waves leave speakers in phase Relative phase along XY depends on

distance travelled Maximum if path difference = n Minimum if path difference = (n + ½)

Light waves

V. rare to observe light interfering to produce dark region

Usually random polarisation and phase Hence no steady interference pattern 1801: Young produced double slit

experiment

Light bands = maxima – due to constrictive interference

i.e. path difference = n Distance between maxima, w depends on:

1. Slit separation, s

2. Wavelength of light, 3. Distance, D between slits and screen

= ws

D