a glass prism is dipped in water will it dispersive power changes ?&why?
Dispersive power of the prism is given by the formula
ω = (μv – μr)/(μ – 1)
here μ – 1 is the mean deviation. Also we can take μ with respect to yellow light as it is midway in the VIBGYOR series. μv and μr are the refractive index of prism for violet and red colours respectively.
Now, when the prism is immersed in water,each of the refractive indices in the above equation will be divided by refractive index of water. Hence numerator will reduce almost by a constant factor. However such will not be the case for denominator.
Hence the denominator will reduce less , as a result , when immersed in water, the dispersive power of the prism increases.