1) Interference patterns can occur for both sound waves and light waves when the conditions of coherence and monochromaticity are met. 2) Young's double slit experiment demonstrated interference of light waves by producing alternating bright and dark bands on a screen, with the spacing of the bands determined by the wavelength, slit separation, and screen distance. 3) All waves, including sound and light, can exhibit constructive and destructive interference depending on the relative phases of the waves, which is determined by path length differences.

1. interference

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

3. Conditions for interference All waves exhibit interference Constrictive Destructive For Interference: The sources must be coherent. The sources should be monochromatic

4. Sound waves

5. 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) 

6. 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

9. Light bands = maxima – due to constrictive interference i.e. path difference = n  Distance between maxima, w depends on: Slit separation, s Wavelength of light,  Distance, D between slits and screen  = ws D