Quelpr
1 markCritical Angle and Total Internal Reflection

CSEC Physics · May/June 2007 · Paper 2 · Question 4(c)(ii)

An optical fibre is a flexible glass rod used to carry light signals. Figure 3 shows an optical fibre with a glass core (refractive index 1.50) surrounded by a cladding (refractive index n₂). Light ray AB in air is refracted into the core along path BC and then totally internally reflected.

Is the refractive index of the cladding greater or smaller than that of the core?

This question uses a figure or table from the paper — you'll see it when you practise.

The mark scheme is shown once you've answered.

Practise this question

Other parts of this question

  1. 4(a)State what these theories considered light to be.[2 marks]
  2. 4(b)Indicate, by ticking the relevant boxes, the properties which these theories can explain. Place an X in the box if the theory CANNOT satisfactorily explain the…[4 marks]
  3. 4(c)(i)What is meant by 'total internal reflection' at point C?[2 marks]
  4. 4(c)(iii)Draw on Figure 3, the ray that shows the path of the light continuing on from C.[1 mark]
  5. 4(c)(iv)Calculate the angle of incidence of the light entering the fibre.[3 marks]
  6. 4(c)(v)Given that the speed of light in air is 3 x 10⁸ m s⁻¹, determine the speed of light in the core of the fibre.[3 marks]

More practice: the rest of this paper · more Critical Angle and Total Internal Reflection questions · all CSEC Physics past papers