Using Huygens' principle and drawing the skteches of wavefront,show how a parallel beam of light is reflected from a polshed surface and hence verify that `anglei=angler`.

Using Huygen's principle and drawing the sketches of wavefronts,show how a parallel beam of ligth is refrated from the surface of separation of a rarer medium to a denser medium .Verify Snell's law.

Explain how a parallel beam of light on reflection from a convex mirror gets diverged.

Explain how a parallel beam of light on reflection from a concave mirror gets converged.

Explain how a parallel beam of light on refraction from a convex lens gets converged.

State Huygens' principle and use it to describe the process of reflection of a parallel beam of light incident on a plane mirror obliquely with the help of a labelled diagram.Prove that the angle of incidence is equal to the angle of reflection.

How is a wavefront defined? Using Huygens' prniciple draw a figure showing the propagation of a plane wave refracting at a plane surface separating two media. Hence verify Snell's law of refraction.

How is a wavefront defined? Using Huygens' prniciple draw a figure showing the propagation of a plane wave reflecting at the interface of the two media. Show that the angle of incidence is equal to the angle of reflection.

State Hugen's principle and verify the laws of reflection of light using this principle.

The principle of 'parallax' is used in the determination of distance of nearby stars. The role of distant object O there is now taken by nearby distant stars. The baseline AB is the line joining the Earth's two locations six months apart in its orbit around the Sun. That is the baseline is about the disameter of the earth's orbit = 3 xx 10^11 m. However, even the nearest stars are so distant that with such a long baseline theyshow parallax only of the order 1 s of arc or so. A parsec is a convenient unit of length on the astronomical sxale. It is the distance of an object that will show a parallar of 1s of arc from opposite ends of a baseline equal to the distance from the Earth to the Sum How much is a parsec in terms of metre?