a
( a)\(C = {\sin ^{ - 1}}\left( {\frac{1}{\mu }} \right)\) and \(\mu \propto \frac{1}{\lambda }\) Yellow, orange and red have higher wavelength than green, so \(\pi\) will be less for these rays, consequently critical angle for these rays will be high, hence if green is just totally internally reflected then yellow, orange and red rays will emerge out.