Final answer:
The intensity of a light source decreases with distance and is inversely proportional to the square of the distance. If the power of the source is halved, the intensity will become 1/4 of the original intensity. To find the distance at which the intensity is the same as before, we need to find the distance at which the intensity is 1/4 of the original intensity.
Step-by-step explanation:
The intensity of a light source is inversely proportional to the square of the distance from the source. If the power of the source is halved, the intensity will become 1/4 of the original intensity. To find the distance at which the intensity is the same as before, we need to find the distance at which the intensity is 1/4 of the original intensity. This would be twice the distance from the original position.
For example, if the original distance was 2 meters and the original intensity was 2.4 W/m², the new distance would be 4 meters and the new intensity would also be 2.4 W/m².