Question

In your provided video of Light and Reflection it is said that light remains undeviated after refraction through a glass slab. But in chapter of human eye it is said while refration through a triangular prism the light ray has angle of deviation and the Two rays intersect if extended. And why in diagrams it is shown that light rays bends away or towards in the left of normal, Why not to the right of the normal.

Answer 1

The light remains undeviated after refraction. In prisms the intersection is due to the refraction at difgediff angles. i.e. in the first case we see the whole white light, so no splitting of light. But in prisms the white light scatters to its components of blue, red, etc. components. They refract at different angles and so intersects. The refraction is towards left because the angle that we use to intersect on prism is same. We give the light from a little bottom to prism. To get the refraction to right we need to intersect light from above the middle part