Why does incident ray falling normally on the surface does not deviate when it passes from one optically transparent medium to another ?
Dear Student
Deviation is the change in direction of the ray when it passes through the lens. The middle portion of the lens is comparatively flat and there is a point on the principal axis and inside the sphere by which all the undeviated rays pass.
Undeviated does not mean that there is no refraction. When we say that there is no deviation, we only mean that the incident ray and the emergent ray are parallel to one another. For thin lenses, the refraction inside the lens is negligible and due to which we represent the ray passing through the optic centre as a straight line. But in the case of a thick lens, we cannot do this.
Regards
Deviation is the change in direction of the ray when it passes through the lens. The middle portion of the lens is comparatively flat and there is a point on the principal axis and inside the sphere by which all the undeviated rays pass.
Undeviated does not mean that there is no refraction. When we say that there is no deviation, we only mean that the incident ray and the emergent ray are parallel to one another. For thin lenses, the refraction inside the lens is negligible and due to which we represent the ray passing through the optic centre as a straight line. But in the case of a thick lens, we cannot do this.
Regards