Question $6$

A plane wave of angular frequency $(=3{10}^{15}Hz)$ and electric field amplitude of $5\frac{V}{m}$ is polarized in the $x-y$ plane, making an angle of $30$ with the $x-$axis. If the wave is propagating in the $-z$ direction, write the mathematical representation for the electric field of the wave.

Question $7$

A glass dish with a plane parallel bottom and of refractive index r$.$i$.=1\mathrm{.}51$ is half$-$filled with water. Then liquid $C{S}_2$ is poured on top of it$,$ and on top of $C{S}_2($r$.$i$.=1\mathrm{.}63),$ a thin cover glass of finite thickness and ri$.=1\mathrm{.}51$ is placed on top of the dish.

A beam of light making an angle of $50$ with the vertical is incident on the horizontal cover glass. Obtain the angles that the incident beam makes with the vertical at each interface till it exits into air again. What conclusion can you draw from the final result?

Question $8$

Light from a He$-$Ne laser