Saturday 14 February 2015

Reflection from spherical mirror

Spherical mirror are of two types (i) Concave mirror and (ii) Convex mirror
Position & nature of image formed by a spherical mirror 

Position of object
Position of image
Size of image in comparison of object
Nature of image

Concave mirror
At infinity
At Focus
Highly diminished
Real, inverted
Between infinity and centre of curvature
Between focus and centre of curvature
Diminished
Real, inverted
At centre of  curvature
At centre of curvature
Of same size
Real, inverted
Between focus and centre of curvature
Between centre of curvature and infinity
Enlarged
Real, inverted
At focus
At infinity
Highly enlarged
Real, inverted
Between focus and pole
Behind the mirror
Enlarged
Virtual, erect
Convex mirror
At infinity
At Focus
Highly diminished
Virtual, erect
In front of mirror 
Between pole and focus
Diminished
Virtual, erect

Note: Image formed by a convex mirror is always virtual, erect and diminished.
Uses of concave mirror:
(i)                  As a shaving glass.
(ii)                As a reflector for the head lights of a vehicle, search light.
(iii)               In ophthalmoscope to examine eye, ear, nose by doctors.
(iv)              In solar cookers.
Uses of Convex mirror:
(i)                  As a rear view mirror in vehicle because it provides the maximum rear field of view and image formed is always erect.
(ii)                In sodium reflector lamp.

Refraction of light: When a ray of light propagating in a medium enters the other medium, it deviates from its path. This phenomenon of change in the direction of propagation of light at the boundary when it passes from one medium to other medium is called refraction of light.
When a ray of light enters from rarer medium to denser medium (as from water to glass) it deviates towards the normal drawn on the boundary of two media at the incident point. Similarly in passing from denser to rarer medium, a ray deviates away from the normal. If light is incident normally on the boundary i.e. parallel to normal, it enters the second medium undeviated.

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