Here's why:
* Inverse Square Law: Light intensity follows the inverse square law. This means that the intensity is inversely proportional to the square of the distance from the source.
* Calculation: If you triple the distance, you're essentially multiplying the distance by 3. When you square this (3 * 3 = 9), the intensity decreases by a factor of 9.
In simpler terms: Imagine the light spreading out from the source like a sphere. As the sphere gets larger (the distance increases), the same amount of light is spread over a larger area, making the light less intense at any given point on the sphere.
