The refractive index of a material changes by 0.014 as the color of the light changes from red to violet. A rectangular slab of height 2.00 cm made of this material is placed on a newspaper. When viewed normally in yellow light, the letters appear 1.32 cm below the top surface of the slab. Calculate the dispersive power of the material.

Given that,


refractive index of a material changes= = 0.014


μv and μr be the refractive indices of violet and red colors


Actual depth = Thickness of slab = t = 2cm


Apparent depth = t = 1.32cm



Therefore,


μy =


= =


Dispersive power = ω =


= =


Thus, the dispersive power of the material is 0.027


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