Refraction, total internal reflection and optical fibres Quiz
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5 questions, one answer each
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1. Light travels at 1.97 × 10⁸ m s⁻¹ in a plastic. What is the refractive index of the plastic?
- A. 0.66
- B. 1.52
- C. 1.97
- D. 5.91
2. A ray passes from air into glass of refractive index 1.50 at an angle of incidence of 30°. What is the angle of refraction?
- A. 19.5°
- B. 20°
- C. 45°
- D. 48.6°
3. Which situation can produce total internal reflection?
- A. Light going from air into water at a large angle
- B. Light going from glass into air at an angle above the critical angle
- C. Light going from glass into air at an angle below the critical angle
- D. Light going from air into glass along the normal
4. The core of a step-index fibre has n = 1.50 and the cladding has n = 1.45. What is the critical angle at the boundary?
- A. 15.0°
- B. 30.0°
- C. 75.2°
- D. 86.6°
5. A fibre link is changed from an LED to a laser emitting a single wavelength. Which effect is reduced the most?
- A. Absorption of light by the glass
- B. Modal dispersion
- C. Total internal reflection
- D. Material dispersion