Question

why are the mirror fitted on the outside of cars convex

Answer 1

Here is answer.......
(1) when an object is kept in front of a convex mirror, we get an erect and diminished image of the object (2) this a convex mirror fitted by the side of a car driver enables him to get an erect, clear and complete view of the vehicles coming from behind. Hence, a convex mirror fitted on the outside of cars

Answer 2

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Convex mirror have the ability to cover more wider field of view by forming diminished and virtual image of the objects . Thus , the mirrors fitted on the outside of cars are convex so that larger view of the road can be observed by the driver sitting in the car .