Diffraction - A Brief Explanation
Diffraction is a wave phenomena which occurs when a wave passes an obstacle or gap. As the wavefront passes the obstacle/gap, it spreads out, the amount of spreading out becoming more pronounced as the wavelength approximates the size of the obstacle or gap more closely. Interference occurs between those different parts of the wavefront on the other side of the obstacle or gap, producing an interference patter. The wavelength of light is very short, betweenandso appreciable diffraction of light only occurs for gaps or obstacles of about this size.