Low beam headlights are aimed at an angle towards the surface. It is designed to light the ground so you can't blind cars ahead of you. In contrast, high beam headlights are aimed straight, similar to a conical beam which provides you maximum visibility at a larger distance. Headlight laws of different states in America require high beams when the visibility is at risk. They must dim their high beams if there's an oncoming vehicle within 500 feet. High beam lights are pointed straight and illuminates roads for 400 feet in front of your car, while low beams are angled to the road to provide clear visibility of the road. A foot-candle is equivalent to one lumen per square foot or the amount of light on a surface of a sphere radius 1 where the candle is placed in the sphere's center.