Optics

Question 1

When does refraction occur?

Answer 1

When a wave passes at an angle across two different mediums with different densities. The wave changed speed and direction and wavelength

Question 2

What is the refractive index of a material?

Answer 2

Speed of light in a free space/ speed of light in the substance
A number bigger than one with no unit

Question 3

What is the refractive index of air?

Answer 3

Around 1

Question 4

What is snells law of refraction?

Answer 4

N1sin Ɵ1= n2sin Ɵ2

Question 5

When does total internal reflection occur?

Answer 5

N1 must be bigger than N2 for total internal reflection to occur
Must be greater than the critical angle

Question 6

What is the function of cladding in a fibre optic?

Answer 6

Has a lower refractive index to reduce light loss from the core

Question 7

What is a step index fibre optic

Answer 7

When there is a change in refractive index from air, to cladding, to core which creates a step like pattern when represented on a graph.

Question 8

What is and what causes material dispersion?

Answer 8

When white light waves travel at different speeds causing the pulses to become longer

Question 9

What is and what causes modal dispersion

Answer 9

When some waves do not undergo total internal reflection and so travels a shorter distance per metre of fibre

Question 10

What is the cause and effect of pulse broadening in a fibre optic?

Answer 10

Cause- when white light is used instead of monochromatic light
Effect- causes material dispersion