What is the shape of the wavefront diverging from a point source of light?

With what type of source of light are cylindrical wavefronts associated?

The refractive indices of glass, diamond and water are $1.5, 2.0$ and $1.33$ respectively. In which of these will the speed of light be maximum? Justify your answer with a suitable reason.

A ray of monochromatic light travelling in vacuum with speed $c$, wavelength $\lambda$ and frequency $f$, enters into a medium of refractive index $1.5$. What will be its new speed, wavelength and frequency?

Out of speed, frequency, wavelength and amplitude, which parameter(s) does (do) not change on reflection?

Is the speed of light in glass independent of the colour of light? Out of red and violet light which one travels slower in a glass prism?