1.Mention difference between interference and diffraction?

	Interference	Diffraction
1	Equally spaced bright and dark fringes	Central bright is double the size of other fringes
2	Equal intensity for all bright fringes	Intensity falls rapidly for higher order fringes
3	Large number of fringes are obtained	Less number of fringes are obtained

2.State malus law?

When a beam of plane polarised light of intensity I₀ is incident on an analyser, the intensity of light I transmitted from the analyser varies directly as the square of the cosine of the angle θ between the transmission axes of polariser and analyser This is known as Malus’ law.

I = I₀ cos²θ

3.List uses of polaroids?

1. Polaroids are used in goggles and cameras to avoid glare of light.
2. Polaroids are used to take 3D pictures i.e., holography.
3. Polaroids are used to improve contrast in old oil paintings.
4. Polaroids are used in optical stress analysis.
5. Polaroids are used as window glasses to control the intensity of incoming light.
6. Polarised laser beam acts as needle to read/write in compact discs (CDs).
7. Polarised light is used in liquid crystal display (LCD).

4.State Brewster’s law?

Brewster’s law states that the tangent of the polarising angle for a transparent medium is equal to its refractive index. The polarising angle is known as Brewster’s angle which dependes on the nature of the refracting medium.

tani_p =  n

5.What is angle of polarisation?

The angle of incidence at which the reflected beam is plane polarized is called polarizing angle or Brewster’s angle (𝒊𝑷) The polarizing angle for glass is ; 𝒊𝑷 = 57.50

6.State Huygens’s principle?

Each point of the wavefront is the source of secondary wavelets emanating from these points spreading out in all directions with the speed of the wave. These are called as secondary wavelets.