Photosynthesis is a process in which green plants and few organisms use sunlight to synthesize their food from carbon di- oxide and water. In plants, during photosynthesis, green pigment known as chlorophyll is involved and oxygen is generated at a by product.
All the sunlight falling on plant is not absorbed. Only half of the falling light which lies in the right frequency to power photosynthesis is absorbed. Out of this falling light, only 8 % to 11% is absorbed by the plant and only 3 % to 6 % is actually used to form chemical energy.