Question Detail
Question
The diagram shows a ray of monochromatic light passing through a semi-circular glass block. The ray emerges in air close to the glass surface. What is the refractive index of the glass?
Correct Answer
Option C is the correct answer.
Detailed Explanation
The diagram implies that the light ray emerges parallel to the flat surface of the glass block, meaning the angle of refraction in air is 90 degrees. The ray is incident on the flat surface from within the glass at an angle that is the critical angle (θc). From the diagram, the angle of incidence in glass (relative to the normal) appears to be 50 degrees. Using Snell's Law for the critical angle: n_glass * sin(θc) = n_air * sin(90°).Given n_air = 1 (for air) and assuming the angle of incidence is 50°.n_glass * sin(50°) = 1 * 1n_glass = 1 / sin(50°)n_glass = 1 / 0.7660 n_glass ≈ 1.305. Rounding to two decimal places, this is 1.31.
Hint
Recall Snell's Law and the definition of critical angle when light travels from a denser to a rarer medium.