Basic physics

1. Mirror used as a reflector in street lamps to diverge light over a large area – Convex.
2. Mirror used as a rear view mirror or driver’s mirror in cars, buses etc.- Convex
3. Mirror used as a reflector in search light, head light of motor vehicles, telescopes, solar cookers etc. – Concave.
4. Mirror used by dentists and ENT specialists to focus light on teeth, eye and throat to examine these organs – Concave.
5. Mirror used as a shaving mirror – Concave
6. Hypermetropia (long sightedness): - A person suffering from this defect can see objects far away but cannot see the nearer object. In this defect eye forms the image of an object behind the retina. This defect is corrected by using a convex (converging) lens of suitable focal length.
7. Myopia (near sightedness) : - A person suffering from this defect can see nearer objects clearly but is unable to see object far away. In this defect eye forms the image of an object behind the retina. This defect is corrected by using a concave lens of suitable focal length.
8. Total internal reflection occurs when light is incident from denser to rarer medium. Example of T.I.R. brilliance of diamonds, mirage, shining of air bubbles in water etc.
9. Optical fibres works on the principle of total internal reflection.
10. In Astronomical telescope image formed is virtual and highly magnified.
11. Primary Colour: - Red , Green and Blue.
12. Red colour is used as a sign of danger signals because of its least scattering.