three cases of refraction of light

Case1: When ray of light travels from rarer medium like air to a denser medium like glass then it bends towards normal.

Case 2: When ray of light travels from denser medium like glass to a rarer medium like air then it bends away from the normal.

Case 3: When ray of light travels from rarer medium like air to a denser medium like glass and again emerges to the previous rarer medium then it suffers a lateral displacement as shown in the figure.

emergent ray

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