Question

A ray of light strikes the glass slab at an angle of 50 what is the angle of incidence

Answer 1

angle of incidence will be  40'

let angle of incidence be i

so,angle made with glass slabs' face by light ray is 50'

and the angle made by ray with incident ray will be angle of <i.

so, that means 50' + <i = 90   {because normal makes <90' with glass slab}

50+<i=90

<i= 90 - 50

<i= 40'

hope this helped you.

please draw the diagram yourself.

it will help you to understand it better