Which of the following statement is correct?

Time taken by light to travel in two different materials $$A$$ and $$B$$ of refractive indices $$\mu_{A}$$ and $$\mu_{B}$$ of same thickness is $$t_{1}$$ and $$t_{2}$$ respectively. If $$t_{2}-t_{1}=5 \times 10^{-10}$$ s and the ratio of $$\mu_{A}$$ to $$\mu_{B}$$ is $$1: 2$$. Then, the thickness of material, in meter is: (Given $$v_{\mathrm{A}}$$ and $$v_{\mathrm{B}}$$ are velocities of light in $$A$$ and $$B$$ materials respectively.)

The speed of light in media 'A' and 'B' are $$2.0 \times {10^{10}}$$ cm/s and $$1.5 \times {10^{10}}$$ cm/s respectively. A ray of light enters from the medium B to A at an incident angle '$$\theta$$'. If the ray suffers total internal reflection, then

The refracting angle of a prism is A and refractive index of the material of the prism is cot (A/2). Then the angle of minimum deviation will be -