The rate of a photochemical reaction is directly proportional to the intensity of light. This relationship is described by the Bunsen-Roscoe Law, also known as the reciprocity law. According to this law, the product of the light intensity I and the exposure time t is a constant k for a given extent of the photochemical reaction.I * t = kAs the light intensity I increases, the time t required for the reaction to reach the same extent decreases, which means the rate of the reaction increases. This is because more photons are available to interact with the reactants, leading to more frequent and efficient molecular collisions and excited states, ultimately resulting in a faster reaction rate.However, it is important to note that this linear relationship between reaction rate and light intensity may not hold true at very high light intensities. At extremely high intensities, the reaction rate may become limited by other factors, such as the availability of reactants, the efficiency of the reaction pathway, or the formation of side products. In such cases, the reaction rate may not increase linearly with light intensity and may even reach a saturation point.