Ray Optics

JEE Main level, single correct, medium

116 of 295

Question 116 of 295

Let the x−zx-z plane be the boundary between two transparent media. Medium 1 in z≥0z \geq 0 has a refractive index of 2\sqrt{2} and medium 2 with z<0z \lt 0 has a refractive index of 3\sqrt{3}. A ray of light in medium 1 given by the vector A⃗=63i^+83j^−10k^\vec{A}=6 \sqrt{3} \hat{i}+8 \sqrt{3} \hat{j}-10 \hat{k} is incident on the plane of separation. The angle of refraction in medium 2 is

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Answer: (A) 45∘45^{\circ}

Normal to the plane is zz-axis
cos⁡θ1=AzA=1020=12,θ1=60μ1sin⁡θ1=μ2sin⁡θ2⇒2×32=3sin⁡θ2⇒θ2=45∘\begin{aligned} & \cos \theta_1=\frac{A_z}{A}=\frac{10}{20}=\frac{1}{2}, \theta_1=60 \\ & \mu_1 \sin \theta_1=\mu_2 \sin \theta_2 \Rightarrow \sqrt{2} \times \frac{\sqrt{3}}{2}=\sqrt{3} \sin \theta_2 \Rightarrow \theta_2=45^{\circ} \end{aligned}

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