WAVES

Question 1

amplitude (A) (waves)

Answer 1

the maximum displacement of the medium from the equilibrium position

Question 2

amplitude (Xo) (smh)

Answer 2

maximum displacement from the equilibrium position

Question 3

analyser

Answer 3

a device that can detect polarised light

Question 4

antinode

Answer 4

position of maximum displacement

Question 5

Brewster’s law

Answer 5

when light reflects off a surface it will be 100% polarised in the plane of the surface if the angle between the reflected and refracted rays is 90 degrees

Question 6

coherent

Answer 6

wave sources that have a fixed phase relationship

Question 7

compression

Answer 7

part of a longitudinal wave where the particles are closest together

Question 8

constructive interference

Answer 8

occurs when waves meet in phase to give maximum displacement

Question 9

critical angle (θc)

Answer 9

angle of incidence above which total internal reflection may occur

Question 10

destructive interference

Answer 10

occurs when waves meet out of phase to give zero displacement

Question 11

diffraction

Answer 11

spreading out of waves past an obstacle or through a gap

Question 12

displacement (x) (smh)

Answer 12

instantaneous distance from the equilibrium position in a specific direction

Question 13

displacement (x) (wave)

Answer 13

the instantaneous distance the medium has moved from the equilibrium position in a specific direction

Question 14

electromagnetic waves

Answer 14

do not require a medium so can travel through a vacuum

Question 15

frequency (f) (wave)

Answer 15

number of oscillations of the medium per second

Question 16

frequency (f) (smh)

Answer 16

number of oscillations per second

Question 17

fundamental frequency (fo)

Answer 17

the lowest frequency standing wave that can be formed in a pipe or on a string

Question 18

intensity (I)

Answer 18

power per unit area received by an observer

Question 19

isochronous oscillation

Answer 19

an oscillation with a constant time period

Question 20

longitudinal wave

Answer 20

the particles of the medium oscillate parallel to the direction of energy transfer

Question 21

Malus’ law

Answer 21

I = Io cos2 θ

Question 22

mechanical waves

Answer 22

require a medium through which to travel

Question 23

node

Answer 23

position of zero displacement

Question 24

optically active substance

Answer 24

substance that rotates the plane of polarised light as the light passes through it

Question 25

path difference

Answer 25

the difference in distance travelled by two different waves, given in terms of wavelength

Question 26

period (T) (smh)

Answer 26

time for one oscillation

Question 27

period (T) (wave)

Answer 27

time for one complete oscillation of the medium (or for a complete wave to pass a given point)

Question 28

polarised light

Answer 28

light in which the electric field vector is oscillating on one plane only

Question 29

rarefaction

Answer 29

part of a longitudinal wave where the particles are furthest apart

Question 30

ray

Answer 30

shows the direction of energy transfer of a wave

Question 31

refraction

Answer 31

the change in speed of a wave that occurs when it travels into a different medium

Question 32

refractive index (n)

Answer 32

a measure of how fast a wave travels in a medium

Question 33

restoring force (shm)

Answer 33

a force that is always directed towards the equilibrium position

Question 34

simple harmonic motion

Answer 34

an oscillation where the force (and acceleration) is proportional to displacement from the equilibrium position but is in the opposite direction

Question 35

Snell’s law

Answer 35

n = sin i / sin r

Question 36

standing wave

Answer 36

a wave formed when a wave is reflected and the reflected wave interferes with the forward moving wave

Question 37

superposition

Answer 37

a resultant wave formed by the addition of the displacements of individual waves when they interfere

Question 38

total internal reflection

Answer 38

occurs when a wave is travelling into a less dense medium and when the angle of incidence at the boundary is greater than the critical angle

Question 39

transverse wave

Answer 39

the particles of the medium oscillate perpendicular to the direction of energy transfer

Question 40

wave

Answer 40

a movement of energy through a medium

Question 41

wave speed (c)

Answer 41

distance travelled per unit time by the energy of the wave

Question 42

wavefront

Answer 42

line connecting points along a wave that are in phase