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Asked in NEET 2022 · Total internal reflection and optical fibres
Given: v_A=1.5×10⁸ m s⁻¹ and v_B=2.0×10⁸ m s⁻¹.
Idea: light is slower in A, so A is the denser medium and total internal reflection happens for a ray going from A into B.
μ_A=c/(v_A)=(3×10⁸)/(1.5×10⁸)=2
μ_B=c/(v_B)=(3×10⁸)/(2.0×10⁸)=1.5
At the critical angle the refracted ray grazes the boundary: μ_A sin C=μ_B sin 90°
sin C=(1.5)/2=0.750
C=sin⁻¹(0.750)
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