Angular Dispersion
The angle subtended between the direction of emergent violet and red rays of light from a prism is called angular dispersion.
Angular dispersion( θ) δ v – δ R =( μ v – μ R) A where δ v and δ R are angle of deviation.
Dispersive Power
W = θ / δ Y =( μ v – μ R) /( μ Y – 1)
where μ Y =( μ v + μ R) / 2, is mean refractive index.
Human Eye
Human eye is an optical instrument which forms real image of the objects on retina.
Retina colours contains lakhs of cone and rod cells which of light and intensities of light respectively.
Ciliary muscles change the focal length of eye lens. This power of eye is called power of accomadation of eye.
Different defects of vision of human eye are described below
( i) Myopia or Short-Sightedness It is a defect of eye due to which a person can see near by objects clearly but cannot see far away objects clearly.
In this defect, the far point of eye shifts from infinity to a nearer distance. This defect can be removed by using a concave lens of