NCERT Physics Class 12 Exemplar Ch 10 Wave Optics Part 2

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Short Answer

Q 16 Can reflection result in plane polarized light if the light is incident on the interface from the side with higher refractive index?

Ans:

• Polarization by reflection occurs when the angle of incidence is the Brewster’s angle i.e. where.

• When light travels in such a medium the critical angle is where

• As for large angles, .

• Thus, polarization by reflection shall definitely occur.

Q 17 For the same objective, find the ratio of the least separation between two points to be distinguished by a microscope for light of and electrons accelerated through used as the illuminating substance.

Ans:

Where ∴is the angle subtended by the objective at the object.

For light of

For electrons accelerated through 100V the deBroglie wavelength is

Q 18 Consider a two slit interference arrangements (Fig.) such that the distance of the screen from the slits is half the distance between the slits. Obtain the value of D in terms ofsuch that the first minima on the screen fall at a distance D from the centre O.

Ans:

Minima will occur when

If