What is Convex Mirror? - Image Formation on a Convex Mirror
Mirrors are surfaces that reflect light creating images of objects in front of them. They are made by painting one surface of the glass with metal amalgams (mostly silver).
Mirrors are of three types: Plane mirror – are a flat mirror. Spherical mirror – are of two types – concave and convex mirror.
It is a spherical mirror curve outward. It is cut out from a glass sphere, and its one surface is painted.
Principal axis is the imaginary line passing through exactly half the height of the convex mirror.
All the rays parallel to the principal axis falling on the surface of the convex mirror seem to meet at a point (on the other side of the mirror). The point is known as the focus or focal point.
The point of intersection between the mirror and the principal axis is called the pole. The distance between the pole and the focus is known as the focal length.
The center of the glass spheres the mirror has been cut from is called the center of curvature. It is an imaginary point. The distance between the pole and the center of curvature is known as the radius of curvature. The radius of curvature is double the focal length.
A convex mirror can also be called a diverging mirror. This is because all the rays falling on its surface seem to be diverging from one point being the focus.
IMAGE FORMATION ON A CONVEX MIRROR
The images formed by a convex mirror is always virtual, upright and diminished. Hence everything appears smaller, and it covers a wider view.
Compared to other reflective mirrors, the field of view for a convex mirror is the maximum. This is because the rays of light falling parallel once reflected diverge. Therefore, it covers are a larger field of view compared to a plane or concave mirror. This one factor allows a very large usage of convex mirrors.
USES OF CONVEX MIRROR
First, convex mirrors are used in the rear-view mirrors of all vehicles. They give a larger view when compared to plane mirrors. We will need huge plane mirrors to cover the width seen through a convex mirror of much smaller size Secondly, for security purposes in building hallways, in shops, etc.
In a shop, one security personnel can view a wide part of the shop using convex mirrors put on the ceiling. Instead of having more than one security personnel we can use multiple convex mirrors on the ceiling.
In hallways, they are put at intersections or at blind spots in the corridors to improve the visibility for people walking there. On roads, driveways, and alleys there are convex mirrors angularly kept especially at curves and turns to improve the visibility. They are also there in parking lots to make parking and taking out of parking easy. The mirror helps them look out at any oncoming traffic or vehicles.
In automated teller machines, there is a convex mirror present close to the top of the machine. This is so that one can see what is behind their back. You can see if anyone is looking while you are entering your pin.
It can be used in sunglasses. It is used in such a way that all the rays of the sun are directed away from the person's eye. Convex mirrors are also used in making of magnifying glasses. Two convex mirrors are placed back to back to create the magnified effect.
They are used in street lights as they are good reflectors of light. They increase the amount of light; this makes it easier to light up streets with low energy usage.