This work is an attempt to understand the nature of light which has been the source for all energy requirement. Propagation of electromagnetic waves and their interaction with matter is still a beautiful mystery. From the pioneering works of Ibn al-Haytham (Kitab al-Manazir) to Newtons' corpuscular theory to the concept of 'packets of energy'propounded by Einstien and Max Planck, study on light has seen a 'wave' of development in different 'phases' whose 'amplitude' cannot be measured. In the present work, coherence properties of light has been analysed for different cases.