Question

when a ray of a light enters a glass slab from air

Answer 1

Heyaaaaa......

Here's your ans......
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When ray of light enters a glass slab from air....as the density in the air is lower than inside the glass slab the ray bends towards the normal....due to refraction...
and again coming in the lighter density area..again the light ray travels as it was traveling before...
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hope this helps...

Answer 2

Heya!

When a ray of light enters a glass slab from air then refraction occurs.
As the ray of light is entering to a denser medium from a rarer medium so it bend towards the normal.

Hope it helps!