| Date | May 2016 | Marks available | 3 | Reference code | 16M.3.SL.TZ0.11 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 0 |
| Command term | Explain | Question number | 11 | Adapted from | N/A |
Question
A ray of monochromatic light enters a graded-index optic fibre.
Draw the path of the ray as it travels through the graded-index optic fibre.
[1]
a.
Explain how the graded-index optic fibre reduces waveguide dispersion.
[3]
b.
Markscheme
curved, symmetrical path
Refraction on entry not required and ignored in diagram for simplicity.
a.
waveguide dispersion means that rays not parallel to the central axis take longer to transmit
in a graded-index fibre rays away from the central axis travel at a higher speed OR rays are «refracted» closer to the central axis OR effective diameter of the fibre is reduced
because refractive index is greater in the centre OR refractive index is less at the edge
b.
Examiners report
[N/A]
a.
[N/A]
b.
