Refraction At A Plane Surface

Question 1

Define a refractive index (n)

Answer 1

Property of a material which measures how much it slows down light passing through it

Question 2

Define Refraction

Answer 2

When a wave enters a different medium, causing it to change direction, either towards or away from the normal depending on the material’s refractive index

Question 3

Total internal Reflection (TIR)

Answer 3

The angle of incidence is greater than the critical angle and the incident refractive index is greater than the refractive index of the material at the boundary

Question 4

Optical Fibres

Answer 4

Flexible thin tubes of plastic or glass which carry information in the form of light signals

Question 5

Absorption

Answer 5

The signal’s energy is absorbed by the fibre, reducing the amplitude of the signal, leading to loss of information.

Question 6

Dispersion

Answer 6

• Causes Pulse broadening
• Received Signal is broader than the transmitted signal
• Broadened signals overlap leading to loss of information

Question 7

Modal Dispersion

Answer 7

• Light rays enter fibre at different angles
• Take different paths along fibre
• Rays take different amounts of time to travel along fibre
• Leads to Pulse Broadening

Question 8

Material dispersion

Answer 8

• Lights of different wavelengths are used
• Light rays travel at different speeds along fibre
• Leads to Pulse Broadening