Final answer:
Concave mirrors are not used in street lights because they focus light into a single point, rather than spreading it out. Convex mirrors are used instead as they distribute the light over a broad area, which is more suitable for street lighting.
Step-by-step explanation:
A concave mirror is not typically used in street lights because of the unique ways in which it interacts with light. Concave mirrors are known as 'converging mirrors' because they focus parallel rays of light onto a single point, known as the focal point. The light emitted by street lights, however, should be directed over a large area, which is achieved by a diverging mirror or lens, like a convex mirror.
To visually understand this, consider a light bulb in the center of a concave mirror. The light rays from the bulb would be reflected by the mirror and converge at the focal point before spreading out. This would be disadvantageous for street lighting as we'd want to illuminate a broad and distant area, not just one concentrated spot.
Compared to concave mirrors, convex mirrors, also known as 'diverging mirrors', diverge light rays, making the light source appear spread out. This makes them an ideal choice for street lights, as they help to diffuse the light over a large area. Despite the fact that a concave mirror can provide a more focused beam of light, this is not the desired effect for street lighting.
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