When passing through an equilateral transparent prism, the minimum deviations experienced by red, yellow, and violet beams are 38.4^ , 38.7^ , and 39.2^ respectively. Determine the dispersive power of the medium.

Step-by-step solution

The dispersive power of a prism is defined as the ratio of angular dispersion to the mean deviation. Angular dispersion is given by the difference in deviation of the extreme colours: = _v - _r Mean deviation is given by the deviation of the yellow light: = _y Therefore, the dispersive power is: = _v - _r _y Substituting the given values: = 39.2^ - 38.4^ 38.7^ = 0.8^ 38.7^ 0.0206