What is dipersion? Obtain the equation for dispersive power of a medium.

Explanation

Dispersive power `omega` is the ability of the material of the prism to cause dispersion. It is defined as the ratio of the angular dispersion for the extreme colours to the deviation for any mean colour. Dispersive power (`omega`),
`omega = ("angular dispersion")/("mean deviation") = (delta _V - delta_R)/(delta)`
Substituting `(delta_V - delta_R)` and (`delta`),
`omega = ((n_V - n_R))/((n - 1))`