3.1 - Progressive and stationary waves

Question 1

what is a progressive wave

Answer 1

transfers energy from one point to another without transferring the medium itself and the particles in the medium oscillate as the wave passes through them

Question 2

define Amplitude

Answer 2

A wave’s maximum displacement from the equilibrium position

Question 3

define frequency

Answer 3

The number of complete oscillations passing through a point per second

Question 4

define wavelength

Answer 4

The length of one whole oscillation (e.g. the distance between successive peaks/troughs)

Question 5

define speed

Answer 5

Distance travelled by the wave per unit time

Question 6

How can you find out the time period of a wave using it frequency?

Answer 6

T = 1/f

Question 7

what is a phaze

Answer 7

a fraction of a wave cycle
how far through the oscillation a point is

Question 8

what is phase difference

Answer 8

the difference in phase between 2 points on a wave

Question 9

what happens if two waves re half a wavelength apart

Answer 9

they are out of phase

Question 10

what is phase difference measured in

Answer 10

radians and degrees

Question 11

what is phase

Answer 11

on the same point on a wave

Question 12

What is antiphase

Answer 12

opposite points on a wave

Question 13

equation for wave speed

Answer 13

wave speed = frequency x wavelength

Question 14

what is a longitudinal wave

Answer 14

A wave in which the oscillation of the particles is parallel to the direction of energy propagation.

Question 15

what are the two components of a longitudinal wave

Answer 15

rarefactions ( areas of low pressure)
compressions (areas of high pressure)

Question 16

what is a transverse wave

Answer 16

a wave in which oscillations occur perpendicular to the direction of energy propergation

Question 17

example of a transverse wave

Answer 17

electromagnetic
water

Question 18

what are mechanical waves

Answer 18

waves that require a medium to propagate

Question 19

what is an electromagnetic wave

Answer 19

vibrating electric and magnetic fields that oscillate at right angles to each other

Question 20

properties of electromagnetic waves

Answer 20

they can travel through a vacuum without a medium
and travel at the speed of light

Question 21

what is unpolarised light

Answer 21

then the electric fields are oscillating in multiple planes

Question 22

what happens if light is polarised

Answer 22

then the electric field is oscillating in one plane only

Question 23

What does a polarising filter do?

Answer 23

causes plane polarisation by only allowing oscillations in one plane. and absorbing all other planes.

Question 24

How is polarisation used as evidence of the nature of transverse waves?

Answer 24

Polarisation can only occur if a wave’s oscillations are perpendicular to its direction of travel (as they are in
transverse waves).

Question 25

what happens when 2 polarising filters are placed at right angles to each other

Answer 25

no light will be transmitted through

Question 26

what are the 3 uses of polarising filters

Answer 26

- reduces glare when photographing by absorbing some reflected light waves - sunglasses - TV aerials

Question 27

How is polarisation used in antennas?

Answer 27

radio signals are 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 28

how can a polarising filter be used to determine if a light is partially polarised

Answer 28

rotate the filter and observe if there is a change in light intensity which alternates every 90 degrees

Question 29

why does light not pass through 2 polarised filters at right angles

Answer 29

as light first passes through polariser 1 it is plane-polarised in the vertical axis so all the horizonal wavelengths are absorbed, so when it then passes through polariser 2 the transmission axis is horizontal so wont allow light to pass trough

Question 30

how does adding a third 45 degree filter alter the light intensity

Answer 30

after polariser 1 the light is vertically polarised but it has a component at 45 degrees which is able to pass through the polariser. This 45 degree wave also has a a component at 45 degrees so the wave is able to pass through the 90 degree polariser

Question 31

what are stationary waves

Answer 31

A wave which transfers no energy and whose positions of maximum and minimum amplitude are constant.

Question 32

what is a node

Answer 32

a point on a stationary wave where the displacement is 0

Question 33

what is an antinode

Answer 33

a point on a stationary wave with maximum displacement

Question 34

What are the conditions for a stationary wave to be produced?

Answer 34

● The waves must be of the same frequency, wavelength and amplitude. ● They must be travelling in opposite directions

Question 35

when are the conditions for a stationary wave met

Answer 35

when a wave is reflected back on itself

Question 36

what is superposition

Answer 36

the process when two waves combine into a single wave form when they overlap the total displacement at a point is equal to the sum of the individual displacements at that point

Question 37

what is constructive interference