Question
Question: A wave front AB passing through a system C emerges as DE. The system C could be – 
A
A slit
B
A biprism
C
A prism
D
A glass slab
Answer
A prism
Explanation
Solution
A slip would give divergent, a biprism would give double, a glass slabs would give a parallel wavefront. Only a prism would turn the wavefront; refracting edge is downwards