Waves

Question 1

Define longitudinal waves

Answer 1

Waves with oscillations or vibrations parallel to the direction of wave propagation.
Has compressions and rarefactions

Question 2

Define transverse waves

Answer 2

Waves with oscillations or vibrations perpendicular to the direction of wave propagation

Question 3

Define wavelength

Answer 3

The distance between 2 similar points on adjacent waves

Question 4

Define frequency

Answer 4

The number of oscillations that occur each second

F=1/T

Question 5

Define displacement

Answer 5

Distance of a point on a wave from its position of equilibrium

Question 6

equilibrium amplitude

Answer 6

Maximum displacement of a wave

Question 7

Define period

Answer 7

The time taken for one complete oscillation

Question 8

Define phasor

Answer 8

Rotating arrows that indicate it’s position on a wave in terms of radians or degrees.
A phasor rotates anti-clockwise

Question 9

Define coherent waves

Answer 9

When 2 waves have the same frequency and wavelength and maintain a constant phase relationship

Question 10

Define the principle of superposition

Answer 10

When 2 wavelengths meet and combine, their displacements combine. The displacements of the superposed wave is the sum of the component waves

Question 11

How do standing waves form?

Answer 11

When 2 progressive coherent waves travel in opposite directions and superpose

Question 12

What happens at nodes and antinodes

Answer 12

Nodes- where the standing waves destructively interfere

Antinodes- where the standing waves constructively interfere

Question 13

progressive waves

Answer 13

move through material (excluding EM), transferring energy from one position to
another

Question 14

mechanical waves

Answer 14

waves that need a medium to travel through

Question 15

phase difference

Answer 15

the proportion of a cycle by which two waves are “out of sync”, measured in
radians.
phase difference of two points on a wave - amount by which one oscillation leads/lags
behind another

Question 16

wave speed

Answer 16

speed with which energy is transmitted by a wave. v= fλ or c= fλ

Question 17

reflection

Answer 17

when waves rebound from a barrier, changing direction but remaining in the same
medium

Question 18

refraction

Answer 18

when waves change direction when they travel from one medium to another due to
difference in wave speed in each medium

Question 19

diffraction

Answer 19

when a wave spreads out after passing around an obstacle or through a gap

Question 20

electromagnetic waves

Answer 20

a self-propagating transverse wave that does not require a medium to
travel through

Question 21

principle of superposition

Answer 21

ability of a waves to pass through each other and temporarily occupy the same space and combine then carry on unaffected

Question 22

interference

Answer 22

the addition (superposition) of two or more coherent waves, resulting in a new wave formed

Question 23

coherence

Answer 23

two waves with a constant phase relationship over a significant period of time. coherent sources emit waves that have a constant phase relationship

Question 24

path difference

Answer 24

the proportion of a wavelength by which two waves are “out of sync”

Question 25

constructive interference

Answer 25

when two waves superpose and reinforce to give an increased amplitude

Question 26

destructive interference

Answer 26

two waves that superimpose and cancel out to give a reduced amplitude

Question 27

monochromatic

Answer 27

light of one wavelength or frequency

Question 28

stationary waves

Answer 28

a wave pattern produced when two progressive waves of the same frequency travelling in opposite directions superpose, and the energy is stored rather than transferred from one place to another

Question 29

antinode

Answer 29

point of maximum amplitude along a stationary wave caused by constructive interference

Question 30

node

Answer 30

a point that always has 0 amplitude along a stationary wave caused by destructive interference

Question 31

fundamental mode of vibration

Answer 31

the simplest stationary wave that can be set up where the length of the string is half the wavelength

Question 32

fundamental frequency

Answer 32

lowest frequency in harmonics series where a stationary wave forms

Question 33

harmonics

Answer 33

whole number multiples of the fundamental frequency of a stationary wave

Question 34

photon

Answer 34

a quantum of energy of electromagnetic radiatio

Question 35

electronVolt

Answer 35

the energy change of an electron when it moves through a potential difference of 1 volt

Question 36

work function φ

Answer 36

minimum energy required by a single electron to escape the metal surface

Question 37

threshold frequency

Answer 37

the minimum frequency required to release electrons from the surface of a metal

Question 38

de broglie equation

Answer 38

an equation expressing the wavelength of a particle as a ratio of planck's constant and the particles momentum

Question 39

emission spectra

Answer 39

a pattern of colours of light, each colour having a specific wavelength

Question 40

absorption spectra

Answer 40

a spectrum of light with dark lines produced when light passes through a cool gas and the gas absorbs certain frequencies depending on the elements in the gas

Question 41

when does total internal reflection take place?

Answer 41

If the value of angle of incidence is greater than the critical angle

Question 42

when does destructive and constructive interference take place?

Answer 42

if 1/2 wavelength difference, destructive interference, if full wavelength difference, destructive interference.