waves

Question 1

progressive waves

Answer 1

a progressive wave transfers energy without transferring material and is made up of particles of a medium oscillating

Question 2

wavelength

Answer 2

the distance between adjacent points that oscillate in phase

Question 3

amplitude

Answer 3

maximum displacement from peak to equilibrium position

Question 4

frequency

Answer 4

the number of cycles per second

Question 5

period

Answer 5

the time for one complete wave to pass a fixed point

Question 6

displacement

Answer 6

distance and direction from its equilibrium position

Question 7

cycle

Answer 7

once complete cycle is from maximum displacement to the next maximum displacement.

Question 8

velocity

Answer 8

how fast the wave is travelling

Question 9

Phase
difference

Answer 9

How much a particle/wave lags behind another particle/wave

Question 10

longitudinal waves
made up of?
can they travell in a vaccum?

example?

Answer 10

oscillations are parallel to the direction of energy transfer

made up of compressions and rarefractions
they cannot travel in a vaccum

sound waves

Question 11

sound waves
type of wave?
direction?
regions of…

can be demonstrated by?

Answer 11

longitudinal
air molecules oscillate parallel to the direction of propagation
regions of high and low pressure travel through the air

can be demonstrated by pushing a slinky horizontally

Question 12

transverse waves

example?

Answer 12

oscillations are perpendicular to the direction of energy transfer

electromagnetic waves

Question 13

electromagnetic waves
consist of…
they all travel..

Answer 13

consist of oscillating electric fields and magnetic fields. neither can exist without eachother
they all travel at the same speed in a vaccum 3x10^8

Question 14

if the electromagnetic wave is POLARISED…

Answer 14

electric field oscillates in one plane only

Question 15

if the electromagnetic wave is UNPOLARISED…

Answer 15

electric field oscillates in multiple planes

Question 16

polarising filter-
what does it do?
2 polarising filters?

Answer 16

it absorbs one component of the electric field and transmits the other
2 polarising filters at right angles would absorb both components so no light is transmitted.

Question 17

what is polarisation evidence for?
why?

Answer 17

evidence for the nature of transverse waves
because polarisation can only occur if a waves oscillations are perpendicular to its direction of travel

Question 18

application of polarisation:
polaroid sunglasses

Answer 18

Polaroid sunglasses are an application of polarisation. They reduce glare by blocking partially
polarised light reflected from water and tarmac, as they only allow oscillations in the plane of the
filter, making it easier to see.

Question 19

application of polarisation:
TV and Radio signals

Answer 19

usually plane-polarised by
the orientation of the rods on the transmitting aerial, so the receiving aerial must be aligned in the
same plane of polarisation to receive the signal at full strength.

Question 20

superposition

t

Answer 20

where the displacements of two waves are combined as they pass each other,
the resultant displacement is the vector sum of each wave’s displacement.

Question 21

what are the two types of interference that can occur during superposition?
when do they occur?

Answer 21

Constructive interference occurs when 2 waves have displacement in the same
direction
● Destructive interference occurs when one wave has positive displacement and the other
has negative displacement, if the waves have equal but opposite displacements, total
destructive interference occurs

Question 22

how is a stationary wave formed?

energy transfer?

Answer 22

A stationary wave is formed from the superposition of 2 progressive waves, travelling in
opposite directions in the same plane, with the same frequency, wavelength and amplitude.

no energy is transferred by a stationary wave

Question 23

antinodes
when are they formed?

Answer 23

regions of maximum amplitude
when the waves meet in phase constructive interference occurs so antinodes are formed

Question 24

nodes
when are they formed

Answer 24

regions of no displacement
when the waves meet completely out of phase, destructive interference occurs and nodes are formed

Question 25

1st harmonic | double frequency?

Answer 25

lowest frequency at which a stationary wave forms. | double the first harmonic frequency to find second harmonic frequency

Question 26

what is the distance between adjacent nodes?

Answer 26

half a wavelength

Question 27

formation of a stationary wave-A string fixed at one end, and fixed to a driving oscillator at the other

Answer 27

A wave travelling down the string from the oscillator will be reflected at the fixed end of the string, and travel back along the string causing superposition of the two waves, and because the waves have the same wavelength, frequency and amplitude, a stationary wave is formed

Question 28

stationary waves-microwaves how are they formed? | finding nodes and antinodes?

Answer 28

the waves are reflected to a metal plate and are superposed with waves travelling in opposite direction. | to find the nodes and antinodes use a microwave probe.

Question 29

stationary waves- sound waves what produces them? how?distance between each node?

Answer 29

a loudspeaker produces stationary soundwaves in a glass tube with powder. the powder laid along the bottom of the tube is shaken away from the antinodes but left undisturbed at the nodes. the distance between each node is half a wavelength and the frequency of the signal generator is known so by c=fλ the speed of sound in air can be found.

Question 30

what does a point source produce?

Answer 30

produces circular wavefronts. this source produces waves of a single frequency/wavelength

Question 31

path difference

Answer 31

difference in the distance travelled by 2 waves

Question 32

what are the conditions for coherence?

Answer 32

a coherent light source will have the same frequency and wavelength and a fixed phase difference

Question 33

# constructive interference when does it take place? path difference? amplitude signal?

Answer 33

if the waves arrive at a certain point in phase then constructive interference will take place. the path difference to this point will be equal to a whole number of wavelengths. large amplitude signal

Question 34

# destructive interference when does it take place? path difference?

Answer 34

if the waves arrive at a certain point in antiphase then destructive interference takes place. this will happen when the path difference.