A) \[{{45}^{o}}\]
B) \[{{60}^{o}}\]
C) \[{{0}^{o}}\]
D) \[{{30}^{o}}\]
Correct Answer: A
Solution :
According to the given condition, the beam light will retrace its path after reflection from BC \[\angle CPQ={{90}^{o}}\] Thus, angle of refraction at surface AC \[\angle PQN=\angle r={{90}^{o}}-{{60}^{o}}={{30}^{o}}\] By Snells law \[\mu =\frac{\sin i}{\sin r}\] \[\Rightarrow \] \[\sqrt{2}=\frac{\sin i}{\sin {{30}^{o}}}\] \[\therefore \] \[\sqrt{2}\times \sin {{30}^{o}}=\sin i\] \[\Rightarrow \] \[\sqrt{2}\times \frac{1}{2}=\sin i\] \[\Rightarrow \] \[i={{45}^{o}}\]You need to login to perform this action.
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