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Q.
If $A B$ is incident wavefront. Then, refracted wavefront is
Wave Optics
Solution:
When $A B C$ wavefront passes through glass, its velocity is reduced.
As, points $A$ and $C$ remain in glass for a short duration, they move for a larger distance and $B$ covers a small distance as it remains in glass for a longer duration (middle portion of glass is thick) and finally $A^{\prime} B^{\prime} C^{\prime}$ is position of new wavefront. It is concave in shape.
