Light introduction

Light Introduction : Light Introduction Light is a form of Energy that help us to see the variety of objects in the world Things become visible only with the help of light Light always travel in a straight line

Reflection : Reflection Bouncing back of Light ray is called reflection. A light ray when it falls on a highly polished surface such as a mirror , reflects most of the light falling on it

Reflection of light : Reflection of light Laws of reflection The angle of incidence is equal to angle of reflection The incident ray, the normal to the mirror at the point of incidence and the reflected ray all lie in the same plane

Properties of image formed by plane mirror : Properties of image formed by plane mirror Image is virtual and erect. The size of the image is equal to that of the object The image is as far behind the mirror as the object in front of it. The image is laterally inverted

Spherical mirrors : Spherical mirrors Mirrors are of two types. 1. Plane mirror 2. spherical mirror For the plane mirror reflecting surface is plane. Mirrors whose reflecting surfaces are spherical are called spherical mirrors. A spherical mirror whose reflecting surface is curved inward is called concave mirror A spherical mirror whose reflecting surface is curved outwards are called convex mirror

Terms used in mirrors : Terms used in mirrors The centre of the reflecting surface of a spherical mirror is called pole The centre of the sphere on which the reflecting surface forms a part is called centre of curvature Radius of the sphere on which reflecting surface forms a part is called radius of curvature

Terms used in mirrors : Terms used in mirrors The line joining the centre of curvature and pole is called principal axis The rays of light after reflection meet at a point on the principal axis .This point is called principal focus. The rays which are parallel to the principal axis that incident on the mirror after reflection appear to meet at a point ,that point is called principal focus of convex mirror.

Focal length : Focal length The distance between principal focus and the pole is called focal length The diameter of the reflecting surface of the spherical mirror is called aperture Radius of curvature is twice the focal length R = 2f

Converging and diverging mirror : Converging and diverging mirror Concave mirror converges all the light rays to a point so it is called converging mirror Convex mirror diverges all the light rays from a point .So convex mirror is called diverging mirror

Rules for drawing ray diagrams in concave mirrors : Rules for drawing ray diagrams in concave mirrors A ray parallel to the principal focus after reflection goes through the focus

Rules for drawing ray diagrams in concave mirrors : Rules for drawing ray diagrams in concave mirrors The ray that is passing through the principal focus after reflection goes parallel to the principal axis

Rules for drawing ray diagrams in concave mirrors : Rules for drawing ray diagrams in concave mirrors The ray that is passing through the centre of curvature after reflection is reflected along the same path

Rules for drawing ray diagrams in concave mirrors : Rules for drawing ray diagrams in concave mirrors The ray that is incident obliquely to the principal axis towards the point p is reflected obliquely

Rules for drawing ray diagram in convex mirror : Rules for drawing ray diagram in convex mirror A ray parallel to the principal axis of a convex mirror appear to diverge from the principal focus

Rules for drawing ray diagram in convex mirror : Rules for drawing ray diagram in convex mirror A ray that is directed towards the principal focus after reflection will emerge parallel to the principal axis

Rules for drawing ray diagram in convex mirror : Rules for drawing ray diagram in convex mirror The ray that is directed towards the centre of curvature after reflection reflected along same path

Rules for drawing ray diagram in convex mirror : Rules for drawing ray diagram in convex mirror The ray that is incident obliquely to the principal axis towards the point p is reflected obliquely

Image formation by concave mirror : Image formation by concave mirror When the object is placed at infinity, the image is formed at the focus of concave mirror Image formed is 1. Highly diminished 2. Real and inverted

Image formation by concave mirror : Image formation by concave mirror When the object is placed beyond the centre of curvature image is formed between the centre of curvature ‘C’ and the focus ‘F’. The image formed is 1. Real and inverted 2. Diminished

Image formation by concave mirror : Image formation by concave mirror When the object is placed at the Centre of curvature of concave mirror, Image is also formed at the Centre of curvature. The image formed is 1.real and inverted 2. same size

Image formation by concave mirror : Image formation by concave mirror when the object is placed between Centre of curvature and Focus of a concave mirror ,the image is formed beyond centre of Curvature The image is 1. Enlarged 2. Real and inverted

The object is placed at ‘F’ Of a concave mirror : The object is placed at ‘F’ Of a concave mirror When the object is placed at ‘F’ the image is formed at infinity The image formed is. highly enlarged Real and inverted

Image formation of an objectwhen it is placed with In the focus. : Image formation of an objectwhen it is placed with In the focus. When the object is placed with in the focus, image is formed behind the mirror. Image is 1.Enlarged 2.Virtual and erect