CLASS IX PHYSICS REFLECTION OF LIGHT AT CURVED SURFACES

REFLECTION OF LIGHT AT CURVED SURFACES

REFLECTION OF LIGHT AT CURVED SURFACES.

LAWS OF REFLECTIONS:  

            (i) Angle of Incidence is equal to  Angle of reflection

            (ii) Incident ray, reflected ray normal at the point of incidence all lie in the same plane.

a) Pole: The centre of the reflecting surface of a spherical mirror is called as Pole. It is

 denoted by ‘P’.

b) Centre of curvature: The centre of sphere, of which the reflecting surface of a

 spherical mirror is a part is called the centre of curvature. It is denoted by ‘C’.

c) Focus: The point on the principal axis at which the parallel rays coming from infinity

 converges after reflection is called focus of the spherical mirror. It is denoted by ‘F’.

d) Radius of curvature: The radius of sphere, of which the reflecting surface of a

 spherical mirror is a part is called the radius of curvature. It is denoted by ‘R’.

e) Focal length: The distance between pole and focus is called focal length of the

 spherical mirror. It is denoted by ‘f’.

 f) Principal axis: The line passing through the pole and centre of curvature of spherical

 mirror is called principal axis of the mirror.

 

g) Object distance: The distance from the pole of spherical mirror to object is called

 object distance. It is denoted by ‘u’.

 h) Image distance: The distance from the pole of spherical mirror to image is called

 image distance. It is denoted by ‘v’.

 

i) Magnification: The relative ratio of size of image formed by spherical mirror to the size

 of object is known as magnification. It is denoted by ‘m’.

Sign convention for the parameters related to the mirror equation

 (i) All distances should be measured from the pole.

 (ii) The distances measured in the direction of incident light, to be taken positive and those

 measured in the direction opposite to incident light to be taken negative.

 (iii) Height of object (Ho) and height of image (Hi) are positive if measured upwards from

 the axis and negative if measured downwards.

The following video you can see about ray diagrams.

tags: pole, ray diagrams,