Y1 Ch 05 Waves

Question 1

Progressive Wave definition

Answer 1

An oscillation or vibration that transfers energy and information not matter.

Question 2

Frequency definition

Answer 2

The number of cycles or vibrations per second, measured in Hertz

Question 3

Period definition

Answer 3

Time per cycle, measured in seconds

Question 4

Amplitude definition

Answer 4

The maximum displacement from the equilibrium line

Question 5

Wavelength definition

Answer 5

The distance between wake peaks or two equivalent points

Question 6

Longitudinal wave definition

Answer 6

A wave where the oscillation is parallel to the direction of travel

Question 7

Transverse wave definition

Answer 7

A wave where the oscillation is perpendicular to the direction of travel

Question 8

Phase difference definition

Answer 8

the fraction of a wave cycle between two points

Question 9

Phase difference equation

Answer 9

2pidistance between the two points/wavelength

Question 10

Polarisation definition

Answer 10

the action of restricting the vibrations of a transverse wave, especially light, wholly or partially to one direction

Question 11

Polarisation only happens to …..

Answer 11

transverse waves

Question 12

How can Light be polarised?

Answer 12

1. Reflection 2. filters 3. through certain materials

Question 13

Why is polarisation used?

Answer 13

1. to reduce glare 2. to reduce interference

Question 14

Refraction explanation

Answer 14

as a wave travels from one material to another it will change speed causing it to change direction

Question 15

Refractive index equation

Answer 15

n = C/Cs

Question 16

Refractive index definition

Answer 16

The ratio of a wave’s speed in a vacuum to the wave’s speed in the substance

Question 17

Snells law

Answer 17

N1 * Sinϴ1 = N2 * Sinϴ2

Question 18

Which has a longer wavelength red light or blue light?

Answer 18

Red light

Question 19

Total Internal Reflection Definition

Answer 19

when all light is reflected off a boundary of 2 materials if different optical densities

Question 20

For TIR to occur the angle of incidence must be bigger than the …

Answer 20

Critical angle

Question 21

How to find the critical angle

Answer 21

Sinϴ = 1/n1

Question 22

What occurs inside an optic fibre so light can be transferred

Answer 22

Total Internal Reflection

Question 23

Why is there cladding on an optic fibre

Answer 23

1. to increase the surrounding refractive index so only light with a shallower path can be reflected 2. to stop light leaking out when the core is damaged

Question 24

What must the refractive index of the cladding of an optic fibre be in terms of the refractive index?

Answer 24

Bigger than air but smaller than the core so it can totally internally reflect

Question 25

Broadening (optic fibres)

Answer 25

The dispersion of pulses - too much broadening causes a reduction in the quality of the signal

Question 26

Pulse broadening limits …

Answer 26

the frequency of pulses sent down an optic fibre

Question 27

What do we do to overcome the material absorbing the light energy?

Answer 27

amplify the signal