Mirrors and Lenses

Use Of Concave Mirrors

Concave mirrors forms large image of closely placed objects.Due to this property, they are used as shaving mirrors and are also used by dentists.

Concave mirrors can concentrate sunrays falling on them at a point and due to this reason they are also used in solar power projects.

Use Of Convex Mirrors

Convex mirrors give a wide field of view although they make things look smaller. Thus, they are used as rear-view mirrors in vehicles, in supermarkets to look for shop lifters and also in buses so that the driver gets the view of whole bus.

Differences Between Plane, Concave And Convex Mirrors

Plane mirror	Concave mirror	Convex Mirror
Reflecting surface is flat	Reflecting surface is curved inwards	Reflecting surface is curved outwards.
Image formed is virtual and erect	Image formed is real and inverted except when the object is closer to mirror.	Image formed is virtual and erect.
Image formed is of the same size as of the object.	Image formed is either enlarged or diminished.	Image formed is diminished.

Convex And Concave Lens

A lens is a curved and a transparent piece of glass or any other material that has two spherical surfaces. When light passes through a spherical surface of lens, it changes its path. This deviation in path of light is called refraction of light.

Lenses are of two types as shown in the flow chart given aside

Concave lens is also called diverging lens because it diverge the parallel beam of light rays falling on it.

A concave lens always gives a virtual, erect and diminished image of an object irrespective of the distance of the object from the lens.

Convex lens is also called converging lens because it
converge the rays
of light passing through it. A nature of image Formed by convex lenses changes with the distance of the object from the lens.

Differences Between Convex And Concave Lens

Convex Lens	Concave lens
It is thicker in the middle and thinner at the edges.	It is thicker at the edges and thinner in the middle.
It converges light rays passing through it	It diverges rays of light passing through it.
The Nature of image vary with the distance between the light source and image.	It forms a virtual, erect and diminished image.

Fact File -Human eyes have a convex lens that collects light from an object and focuses on the retina.