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Posted by on Jan 24, 2016 in Tell Me Why |

Why Do Cars Have Side-view Mirrors with the Message, “objects in the Mirror Are Closer than They Appear”?

Why Do Cars Have Side-view Mirrors with the Message, “objects in the Mirror Are Closer than They Appear”?

Car manufactures are required to provide flat, unit magnification mirrors on the driver’s side of the car. The driver-side mirror offers the same undistorted image as the mirror in your medicine cabinet. The new mirrors are convex (for those who forgot their high school science, convex surfaces curve outward, as opposed to a spoon, which has a concave surface).

Convex mirrors have one huge advantage over flat mirrors – they allow a much wider angle of vision. Engineers have found that convex side-view mirrors afford drivers a much clearer view of the passenger side of the car than the old combination of rear-view mirror and conventional side-view mirror.

The rear-view mirror, if used alone, leaves a blind spot that can lull drivers into complacency when they are considering making lane changes. Drivers are less likely to be sideswiped when consulting a wide-angle side-view mirror, even if an oncoming car is closer than it appears, because they are more likely to spot the car in the first place.

The message “Objects in the mirror are closer than they appear,” is mandated by law on all convex mirrors. The government has also set specific standards for the curvature of convex mirrors. The average radius of the curvature for convex mirrors should be no less than thirty-five inches and no greater than sixty-five inches.

Convex mirror are particularly popular with freeway and turnpike drivers, who can see oncoming cars streaming in from entry ramps much easily. The biggest danger of the convex mirror is that because objects in the mirror appear closer than they appear, drivers will think they have more room to pass another car than they really do.

But most drivers look through the undistorted rear-view mirror rather than the side-view mirror before making a lane change anyway, and the prudent driver should check over his shoulder before making his move.

Content for this question contributed by Kim McDonald, resident of Cleveland, Cuyahoga, Ohio, USA