Question

when a ray of light is incident perpendicularly on a transport glass slab what will be its angle of deviation

Answer 1

According to Snell’s Law, sini/sinr=u

Now sini is zero as angle of incidence i is zero when ray is perpendicular to surface (it is parallel to normal)

so sinr is also equal to zero, means ‘r’ angle of refracted ray is also zero (it is also parallel to normal)

Clearly, both rays are parallel to normal and ther eis no deflection.