3. Waves Key Terms

Question 1

Progressive wave

Answer 1

A wave which transfers energy from one place to another, without the transfer of matter

Question 2

Transverse wave

Answer 2

A wave that oscillates perpendicular to the direction of travel, particles dont move along the direction of the wave

Question 3

Longitudinal wave

Answer 3

A wave that oscillates parallel to the direction of travel

Question 4

Amplitude

Answer 4

The maximum displacement of the wave from its undisturbed position

Question 5

Frequency of wave

Answer 5

The number of oscillations that pass a point in 1 sec. Or the number of complete oscillations in 1 sec.

Question 6

Time period

Answer 6

The time taken to complete 1 whole oscillation

Question 7

Wave length of progressive wave

Answer 7

The distance between the same adjacent points on a wave which are in phase with each other

Question 8

Range of visible wavelengths

Answer 8

400nm - 700mm
Violet - Red

Question 9

Wave speed

Answer 9

How fast the speed moves due to the frequency and wave length

Question 10

In phase

Answer 10

The same cycle or period of a wave
0 degree difference

Question 11

Antiphase

Answer 11

Directly opposite in the same cycle
180 degree difference

Question 12

The principle of superposition

Answer 12

When two waves on the same plane have the same frequency so can combine their individual displacements to give a bigger total displacement

Question 13

Coherence

Answer 13

The waves have the same frequency and a constance phase difference which enables them to superpose

Question 14

Phase difference

Answer 14

The difference between two waves in the same cycle. There can be any degree of phase difference

Question 15

Standing wave

Answer 15

When two coherent waves meet and superpose. Makes it look like it is stationwary however particles are displacing constantly up and down

Question 16

Node

Answer 16

The point on a standing wave where there is no displacement, it doesn’t move

Question 17

Antinode

Answer 17

The point on a standing wave where it has its maximum displacement, it is constantly moving

Question 18

Harmonic

Answer 18

The amount of fundamentals created on a standing wave

Question 19

Fundamental mode

Answer 19

Where there is a single loop which equals half the wavelength of the wave.

Question 20

In phase on a standing wave

Answer 20

There are multiple points on a standing wave that are in phase along each fundamental mode as well as on the opposing wave

Question 21

Path difference

Answer 21

The difference in distance travelled by two waves, it is expressed by a number or of a fraction of a wave

Question 22

Phase difference

Answer 22

The difference in positions of 2 points within a cycle of an oscillation

Question 23

Double slit experiment

Answer 23

wavelength = distance between slits x distance between maximas / distance between light source and maximas

Question 24

Refraction grating

Answer 24

n x wavelength = distance x sinA

Question 25

Snells law

Answer 25

n1sin1 = n2sin2

Question 26

Refractive index

Answer 26

refractive index = speed of light / velocity of particle

Question 27

Critical angle working

Answer 27

n1sin1 = n2sin90

Question 28

Critical angle definition

Answer 28

The largest angle of incidence at which refraction can occur

Question 29

Multipath dispersion

Answer 29

The result of light taking different paths down an optical fibre, this could lead to the merging of data and incorrect readings after the transmission

Question 30

Monomode fibre

Answer 30

An optical fibre where light can only take 1 path Also the most efficient cable with the most data transfer Higher data transfer rates across a much longer distance

Question 31

Polarisation

Answer 31

When waves are changed to one oscillate in a single plane, only happens with transverse waves

Question 32

How can light be polarised?

Answer 32

Using a polarisation filter By reflection By scattering

Question 33

what happens to the amount of diffraction when the gaps are small

Answer 33

the diffraction is bigger

Question 34

when the gaps are bigger what happens to the diffraction

Answer 34

it gives a smaller amount of diffraction

Question 35

What happens to the wavelength when the wave diffract

Answer 35

It doesnt change

Question 36

the amount of diffraction ( the angle of spreading) means...

Answer 36

this depends on the wavelength and the size of the gap

Question 37

what does the angle of incidence equal to

Answer 37

the angle of reflection

Question 38

Wave speed equation

Answer 38

c or v = f x wavelength

Question 39

What is two source interference

Answer 39

When two waves from two different sources superpose and form a new wave

Question 40

What is youngs double slit experiment

Answer 40

When a wave is passed through two slits creating a pattern of maxima and minima on the screen

Question 41

How was youngs double slit experiment important

Answer 41

It showed that light could act as a wave as well as a particle

Question 42

Why is using a diffraction grating better than the double slit experiment

Answer 42

It gives a clearer more defined pattern on the screen and it spreads out the pattern more, it is easier to measure between maximas

Question 43

What is a characteristic of a coherent wave

Answer 43

They are monochromatic Constance phase difference

Question 44

What is the refractive index

Answer 44

The ratio of the speed of light in a vaccum to the speed of light in that medium

Question 45

What happens with total internal reflection

Answer 45

When the light beams reflects off the medium boundary when the angle of incidence is above the critical angle

Question 46

Why is total interal reflection important

Answer 46

It allows data to travel very fast through optical fibres