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