# Which mirror is used in headlights of cars? At what position is bulb placed in it and why?

Concave mirror is used in headlights of vehicles, because when the bulb of headlight is placed at focus of concave mirror, it allows the light to spread out to infinity (longer distances). A concave mirror is a converging mirror as opposed to a convex mirror which is a diverging mirror. A convex mirror always diverges the rays of light falling onto it. Therefore, it is not used as headlights in cars.