Show that lateral shift is equal to the thickness of the slab for grazing incidence.

Explanation

`i=90^(@)`
`r=C=` critical angle
`therefore " Lateral shift"=(t sin(90^(@)-C))/(cosC)`
`L.S=(t cosC)/(cosC): L.S=t`
`therefore` For grazing incidence, there will be grazing emergence. So L.S = t.