Answer: 69.6.
- A 41.8°
- B 48.6°
- C 61.0°
- D 69.6°
Correct answer: D. 69.6°
Explanation: sinθ<sub>c</sub> = n<sub>clad</sub>/n<sub>core</sub> = 1.50/1.60 = 0.9375, so θ<sub>c</sub> = 69.6°.
Concave mirror ray construction: a ray parallel to the axis reflects through F, and a ray through F reflects parallel, locating the inverted real image. Image: Maxmath12, CC0, via Wikimedia Commons.
Concept context
Reflection, refraction, lenses, mirrors, total internal reflection.