Waves Definitions

Question 1

Amplitude

Answer 1

A wave’s maximum displacement from its equilibrium position.

Question 2

Antinodes

Answer 2

A position of maximum displacement in a stationary wave

Question 3

Coherence

Answer 3

Waves with the same frequency and constant phase difference. There are two types of coherence: spatial and temporal coherency. They must also be coming from the same source to avoid a change in phase difference.

Question 4

Constructive Interference

Answer 4

The type of interference that occurs when two waves meet in phase. The wave amplitudes are superposed.

Question 5

Critical Angle

Answer 5

The angle of incidence that results in an angle of refraction of exactly 90o . It is when the refracted ray travels along the boundary line.

Question 6

Destructive Interference

Answer 6

The type of interference that occurs when the two waves are in antiphase. When one wave is at a peak and one is at a trough their addition results in a minimum point

Question 7

Diffraction

Answer 7

The spreading of waves as they pass through a gap of a similar magnitude to their wavelength.

Question 8

Displacement

Answer 8

The distance that a point on a wave is from its equilibrium position

Question 9

Electromagnetic Spectrum

Answer 9

The spectrum of electromagnetic waves, consisting

of Gamma Rays, X-Rays, Ultraviolet, Visible Light, Infrared, Microwaves and Radiowaves.

Question 10

Electromagnetic Waves

Answer 10

Waves that consist of perpendicular electric and magnetic oscillations. All electromagnetic waves travel at the speed of light in a vacuum.

Question 11

Frequency

Answer 11

The number of waves that pass a point in a unit time period. It is the inverse of the time period.

Question 12

Fundamental Mode of Vibration:

Answer 12

The oscillation of a wave at its natural frequency

Question 13

Intensity

Answer 13

The power transferred per unit area. It is proportional to the square of a wave’s amplitude.

Question 14

Interference

Answer 14

The superposition of the amplitudes of waves when they meet

Question 15

Longitudinal Waves

Answer 15

A wave with oscillations that are parallel to the direction of
energy propagation. Sound waves are an example of a longitudinal wave. They cannot travel through a vacuum.

Question 16

Nodes

Answer 16

A position of minimum displacement in a stationary wave

Question 17

Path Difference

Answer 17

A measure of how far ahead a wave is compared to another wave, usually expressed in terms of the wavelength.

Question 18

Period

Answer 18

The time taken for a wave to complete one full cycle

Question 19

Phase Difference

Answer 19

The difference in phase between two points on a wave. It is usually expressed in radians.

Question 20

Polarisation

Answer 20

The restriction of a wave so that it can only oscillate in a single plane. This can only occur for transverse waves

Question 21

Progressive Waves

Answer 21

Waves that transfer energy from one point to another

without a transfer of matter.

Question 22

Reflection

Answer 22

The bouncing of a wave at a boundary. The angle of incidence will equal to the angle of reflection

Question 23

Refraction

Answer 23

The changing of speed of a wave as it passes into a new medium. If light passes into an optically denser medium, it will slow down.

Question 24

Refractive Index

Answer 24

A material property that is equal to the ratio between the speed of light in a vacuum, and the speed of light in a given material.

Question 25

Stationary Wave

Answer 25

A wave that stores, but does not transfer, energy

Question 26

Superposition

Answer 26

When two waves meet at the same point in space their
displacements combine and the total displacement at that point becomes the sum of the individual displacements at that point.

Question 27

Total Internal Reflection

Answer 27

An effect that occurs in optical fibres, where full
reflection occurs at the inside boundary of the fibre, meaning no radiation passes out. The angle of incidence must be greater than the critical angle for this to occur. The incident ray must also be travelling in a more dense medium into a less dense medium.

Question 28

Transverse Waves

Answer 28

A wave with oscillations that are perpendicular to the

direction of energy propagation. Electromagnetic waves are examples of transverse waves.

Question 29

Wavelength

Answer 29

The distance between two identical positions on two adjacent waves. It is commonly measured from peak to peak or trough to trough

Question 30

Young Double-Slit Experiment

Answer 30

An experiment that demonstrates the diffraction of light by passing monochromatic light across two narrow slits and observing the resulting pattern of bright and dark fringes.