Ans. DIFFRACTION
The bending or spreading of waves around the sharp edges or comers of obstacles is called diffraction.
To observer the phenomenon of diffraction of water waves, generate plane waves in a ripple tank and place two obstacles in line in such a way that separation between them is equal to the wavelength of water waves. After passing through a small slit between the two obstacles, the wave will spread in every direction and change into almost semicircular pattern (Fig. 10.13). Diffraction of waves can only be observed if the size of the obstacle is comparable with the wavelength of the wave. Figure 10.14 show the diffraction of waves while passing a slit with size larger than the wavelength of the wave. Only a small diffraction occurs near the comers of the obstacle.