Final answer:
The distance at which visible light can be seen varies and depends on several factors such as light intensity and pupil size. Headlights that are 1.3 meters apart can be resolved at a certain distance according to the resolving power of the human eye, but exact distances like '10 ft' cannot be provided without specific data.
Step-by-step explanation:
The distance at which visible light from a source can be seen depends on several factors, including the intensity of the light, the darkness of the surrounding environment, the size of the pupil, and the sensitivity of the retina. When trying to resolve two points of light, such as the headlights of a car, the resolving power of the human eye comes into play. The minimum angle of resolution for the human eye, which is about 1 arcminute (1/60 of a degree), can be used along with the diameter of the pupil to calculate the maximum distance at which car headlights, which are 1.3 meters apart, can be resolved.
At night, your pupil size increases to let in more light, enhancing your ability to see distant light sources. While specific numbers like '10 ft' or '20 ft' are not mentioned in the provided information, the principle of inverse square law for light intensity is important. According to this law, as you move away from a light source, the intensity of light decreases with the square of the distance. This means that visibility decreases rapidly as distance increases. For example, the light intensity from a car's headlights would become more difficult to resolve as the distance between the observer and the headlights increases.