Prism is uniform transparent medium bounded between two refracting surfaces, inclined at an angle.
Angle of Deviation
The angle subtended between the direction of incident light ray and emergent light fay from a prism is called angle of deviation (δ).
The refractive index of material of prism
Dispersion of Light
The splitting of white light into its constituent colours in the sequence of VIBGYOR, on passing through a prism. is called dispersion of light.
The refractive index μv > μR therefore violet colour deviates most and red colour deviates least. i.e., δv > δR.
The angle subtended between the direction of emergent violet and red rays of light from a prism is called angular dispersion.
(θ) δv – δR = (μv – μR A
where δv and δR are angle of deviation.
W = θ/δY = (μv – μ R) / (μY – 1)
where μY = (μ v + μ R ) / 2, is mean refractive index.