Which of the following generates a plane wavefront?

The direction of wavefront of a wave with wave motion is,

Which one of the following phenomena is not explained by Huygens' construction of wavefront?

Wavefront is the locus of all points where the particles of the medium vibrate with the same,

A parallel beam of monochromatic light is incident on a glass slab at an angle of incidence $45^{\circ} .$ Find the ratio of width of beam in air to that in glass (If refractive index of glass is $1.5$).

On a hot summer night, the refractive index of air is the smallest near the ground and increases with a height from the ground. When á light beam is directed horizontally, the Huygens' principle leads us to conclude that as it travels, the light beam

A parallel beam of monochromatic light is incident on a glass slab at an angle of $35^{\circ} .$ The ratio of width of beam in glass to that in air is$\left[{\mu }_{\mathrm{g}}=1.5\right]$

For passage of monochromatic beam of light in a medium of refractive index $1.5$, the plane wavefront makes an angle of$60°$  with the refracting surface. The ratio of the width of beam in medium to that in air is