NCERT Solutions for Chapter: Wave Optics, Exercise 2: VSA

Is Huygens' principle valid for longitudinal sound waves?

Consider a point at the focal point of a convergent lens. Another convergent lens of short focal length is placed on the other side. What is the nature of the wavefronts emerging from the final image?

What is the shape of the wavefront on earth for sunlight?
 

Why is the diffraction of sound waves more evident in daily experience than that of light wave?

The human eye has an approximate angular resolution of $\varphi =5.8\times {10}^{-4}$ rad and a typical photo printer prints a minimum of $300$dpi (dots per inch, $1$ inch $=2.54$ cm). At what minimal distance $z$ should a printed page be held so that one does not see the individual dots.

A polaroid (I) is placed in front of a monochromatic source. Another polaroid (II) is placed in front of this polaroid (I) and rotated till no light passes. A third polaroid (III) is now placed in between (I) and (II). In this case, will light emerge from (II). Explain.