When the distance is increased three times, the light reaching you is one-ninth as much. When light shines on a light meter, a small electric current is generated. A meter measures the strength of the current. Light is one form of energy we use almost constantly. Your ability to see depends on light.
Light is important in other ways as well.
Plants could not live without light. All living things depend on the food that plants make. Fossil fuels are formed from the remains of once living organisms that depended on light. Scientists have developed many instruments that use light. Light helps man learn about his world by using the microscope and telescope.