Waves Vocab

Question 1

longitudinal wave

Answer 1

displacement of particles in medium is parallel; to direction in which the wave transfers energy

Question 2

transverse wave

Answer 2

displacement of particles in medium is perpendicular; to direction in which wave transfers energy

Question 3

wave direction

Answer 3

direction of energy transfer for a wave

Question 4

wave frequency

Answer 4

the number of waves that pass a point every second

Question 5

wave speed

Answer 5

distance travelled per unit time; by a wavefront

Question 6

amplitude

Answer 6

the maximum displacement of the medium from its equilibrium position

Question 7

coherence

Answer 7

a constant phase difference between waves from different sources

Question 8

monochromatic

Answer 8

an e-m wave of just one frequency/just one wavelength

Question 9

ray

Answer 9

line indicating wave direction; perpendicular to wavefronts

Question 10

wavefront

Answer 10

a line joining points on the wave that have the same phase / displacement; perpendicular to rays

Question 11

plane polarised wave

Answer 11

a transverse wave; where the medium oscillates in just one plane N.B. only transverse waves can be polarised

Question 12

Malus’s law

Answer 12

the intensity of light transmitted by a polarising filter is I = I₀cos²θ

where:

I₀ is the initial intensity of the incident light

I is the intensity of the transmitted light

θ is the angle between the axis of the filter and the direction of polarisation of the light

Question 13

principle of superposition

Answer 13

where two or more waves meet; the resultant displacement at any point is found by adding the displacements produced by each individual wave

Question 14

constructive interference

Answer 14

where waves meet and are in phase; larger amplitude oscillations result

Question 15

destructive interference

Answer 15

where waves meet and are out of phase; smaller amplitude oscillations result

Question 16

standing wave

Answer 16

a standing wave is formed when two waves travelling in opposite directions meet and interfere. They must be of the same frequency.

Question 17

fundamental frequency

Answer 17

the lowest frequency of standing wave that can exist within a system (also called the 1st harmonic)

Question 18

node

Answer 18

a point on a standing wave where the amplitude of the oscillation is zero

Question 19

antinode

Answer 19

a point on a standing wave where the amplitude of the oscillation is at a maximum.

Question 20

amplitude

Answer 20

the MAX distance a wave reaches form rest point

Question 21

wavelength

Answer 21

the DISTANCE for 1 complete oscillation

Question 22

period

Answer 22

the TIME for 1 complete oscillation

Question 23

frequency

Answer 23

The nuber of oscillations in 1 second

Question 24

Displacement

Answer 24

Distance travelled by a wave in a certain direction.

Question 25

Phase difference

Answer 25

The fraction of a cycle between the oscillations of two particles, expressed in degrees.

Question 26

Reflection

Answer 26

The bouncing back of a wave from a surface.

Question 27

Refraction

Answer 27

The change in direction of a wave as it crosses an interface between two materials where it’s speed changes.

Question 28

Diffraction

Answer 28

The spreading of a wave when it passes through a gap or past the edge of and object.