Can anyone me learn malus's law in optics?

It is also called law of Malus,the law states that the intensity of a beam of plane-polarized light after passing through a rotatable polarizer varies as square of the cosine of the angle through which the polarizer is rotated from the position that gives maximum intensity expand.

Before u can know it u have to understand it, so go through it over and over again and u will get it.

The answer is water molecules are split.cellular respiration and photosynthesis are complement  reactions to each other. these are reverse reactions. in cellular respiration glucose and oxygen yield water and carbon dioxide. so, when respiration begins,  glucose molecules are split. in the opposite reaction - in photosynthesis, carbon dioxide and water yield glucose and oxygen. thus,  when respiration begins, water molecules are split.