Light

• Light travels along a straight line.
• The speed of the light is 3*10 to the power 8 m/s.
• When light falls on a smooth/shiny surface the light gets reflected back at the same angle.

Reflection Of Light:

• The surface of water acts like a mirror and change the path of light.
• The change of direction of light at an angle is called reflection of light.
• On a rough surface  the light rays gets scattered.
• An image formed by the plane mirror is erect and is of the same size as that of the object.
• The image on the screen which could not be obtained by a plane mirror is called a Virtual Image.
• White light is composed of seven colours- Red, Orange, Yellow, Green, Blue, Indigo and Violet.

Spherical Mirror:

• Spherical mirror is a curved mirror.
• Spherical mirrors are both concave and convex.
• Concave mirror is also known as converging mirror.
• Concave mirror reflects the light towards inward to one focal point.
• Convex mirror is also known as the diverging mirror.
• Convex mirrors can form images of objects spread over a larger area.
• The outer side of the convex mirror is reflecting.
• The image formed by the concave mirror can be smaller or larger in size then the object.
• The image may also be real and virtual.

Uses Of Concave Mirrors:

• Doctors use concave mirrors to examine our eyes, ears etc..
• Dentists use concave mirrors so that they get the enlarged image of the teeth.
• Headlights of cars and scooters are concave in shape.
• Astronomical Telescopes have concave mirrors.
• Concave mirrors are used in shaving mirrors.

Uses Of Convex Mirrors:

• Convex mirrors are used in traffic lights.
• Convex mirrors are used as the rear view mirror in vehicles.
• Convex mirrors are used inside buildings.
• Magnifying glass have convex mirrors inserted in it.
• The sunglasses which we use are also made up of convex mirrors.

Lenses:

• A transparent material with curved sides for dispersing light rays is known as Lens.
• Lenses are widely used in spectacles, telescopes etc..
• The lenses which are thicker in the middle than at the edges are convex lenses.
• Convex lenses are also called as converging lens.
• The lenses which are thinner in the middle than at the edges are concave lenses.
• The concave lenses are also called as Diverging Lens.
• We can see the image formed by the lens from the side opposite to that of the object.
• The image formed by a convex lens can be real, inverted or virtual ,erect.
• However the image formed by the Concave lens is always erect, virtual and smaller than the object.