P12 Wave properties

Question 1

what are the categories for waves?

Answer 1

transverse
or
longitudinal

Question 2

what do waves do?

Answer 2

transfer energy from one place to another

Question 3

what are transverse waves?

Answer 3

a wave where the oscillations are perpendicular to the direction of energy transfer

Question 4

what are rarefractions?

Answer 4

regions in a longitudinal wave where particles are spread out

Question 5

what is a longitudinal wave?

Answer 5

a wave which has oscillations parallel to the direction of energy transfer

Question 6

what do all longitudinal waves need to travel?

Answer 6

a medium

Question 7

what travels, the medium or the wave?

Answer 7

the wave
the medium does not travel along the wave

Question 8

what is the amplitude of a wave?

Answer 8

the maximum displacement of a point on a wave from its undisturbed position

Question 9

what is the wavelength of a wave?

Answer 9

the distance from a point on one wave to the equivalent point on the adjacent wave

Question 10

what does lambda mean?

Answer 10

wavelength

Question 11

what is frequency?

Answer 11

the number of wave passing a point each second

Question 12

what is the unit of frequency?

Answer 12

the Hertz (Hz)

Question 13

what is the period of a wave?

Answer 13

the time (in seconds) for one wave to pass a point

Question 14

what is wave speed?

Answer 14

the speed at which a wave moves through a medium

Question 15

what is the equation of wave speed?

Answer 15

v = frequency (Hz) x wavelength (m)

Question 16

how can you investigate the speed of sound waves?

Answer 16

two people stand 500m apart, one is holding cymbals (person A) while the other is holding a timer (person B).
person B starts the timer when they see person A crash the cymbals and stop it when they can hear the sound.
then they divide the distance by the time taken to work out the speed

Question 17

what are some problems with the method of investigating the speed of sound waves?

Answer 17

every person has a different reaction time - can be reduced with multiple observers with timers
time between seeing and then hearing the cymbals is very short - increase distance between people

Question 18

what is the easiest way to measure different properties of a water wave?

Answer 18

the ripple tank using a phone so that you can watch it at different speeds or freeze the image

Question 19

how do you measure the wavelength of water waves in a ripple tank?

Answer 19

freeze the image taken on a phone
measure the distance of 10 waves in total using a ruler
divide the result by 10 to get 1 wavelength

Question 20

how do you calculate the frequency of water waves in a ripple tank?

Answer 20

use a time and count the number of waves passing a point in 10 seconds.
then divide the result by 10 to get the number of waves passing a point in 1 second

Question 21

what is another way to work out the wave speed of water waves in a ripple tank?

Answer 21

select a wave and measure the time it takes for it to move the length of the tank.
then divide the distance travelled by the time taken to work out the speed

Question 22

how do you measure the wavelength of a standing wave?

Answer 22

measure from the wooden bridge to the vbration generator

Question 23

how do you know the frequency when investigating waves in a solid?

Answer 23

you know the frequency from the signal generator

Question 24

what can you see from the investigation of wave speed in solids?

Answer 24

the wave speed is not dependent on the frequency or wavelength
it depends on the taughtness of the string and the mass/cm of the sting

Question 25

what could happen when a wave hits a boundary with a different material?

Answer 25

- it could be transmitted through the material - the energy of the wave could be absorbed by the material - it could be reflected off the surface of the material

Question 26

what is the incident ray?

Answer 26

the ray of light which strikes the surface of the reflective material

Question 27

what is the normal?

Answer 27

the line drawn perpendicular to the surface of the mirror or other material

Question 28

what is the angle of incidence?

Answer 28

the angle between the incident ray and the normal

Question 29

what is the rule of reflection?

Answer 29

the angle of incidence equals the angle of reflection

Question 30

what is used to investigate reflection and refraction of light rays?

Answer 30

a ray box, lens and slit

Question 31

in the investigation of reflection and refraction of different materials, what will you find about the angles of reflection and refraction of different materials?

Answer 31

the angles of incidence and reflection are the same for each material investigated this is because these angles do not depend on the material the angle of refraction will be different for each material this is because the angle of refraction is different for different materials

Question 32

what can sound waves in air do to a solid?

Answer 32

trigger vibrations in a solid this only works for a limited range of frequencies

Question 33

what is the frequency range of human hearing?

Answer 33

20 Hz to 20 000 Hz

Question 34

why can frequencies outside the human frequency range not be heard?

Answer 34

they may not be able to make the human ear drum vibrate

Question 35

what happens when waves move from one medium to another?

Answer 35

the speed can change the wavelength also changes

Question 36

what does not change when a wave changes medium?

Answer 36

the frequency of the wave this is because the wave would have to be destroyed or created at the boundary for the frequency to change and that is not possible

Question 37

what does the frequency mean about a sound wave?

Answer 37

the frequency is the pitch of the sound a high frequency has a high pitch a low frequency has a low pitch

Question 38

what does the amplitude mean about a sound wave?

Answer 38

the volume of the sound depends on the amplitude a small amplitude has a quiet sound a large amplitude has a loud sound

Question 39

why can sound waves not pass through a vacuum?

Answer 39

sound waves need a medium to travel as they move by vibrating particles in a vacuum, there are no particles so the sound wave cannot pass through

Question 40

what is an echo?

Answer 40

a reflected sound wave

Question 41

what is ultrasound?

Answer 41

sound waves with a frequency higher than the upper limit of human hearing

Question 42

what do ultrasound waves do do at boundaries of two different densities?

Answer 42

they partially reflect

Question 43

what does ultrasound scanning work for?

Answer 43

organs not surrounded by bone

Question 44

what is the formula for distance when using ultrasound?

Answer 44

s (distance) = v (speed) x t

Question 45

what is the structure of the earth?

Answer 45

outer crust solid mantle with some parts that can flow liquid outer core solid inner core

Question 46

when does an earthquake happen?

Answer 46

when there is a sudden movement of the earth's tectonic plates

Question 47

what are the properties of P waves?

Answer 47

they are longitudinal they can pass through liquids and solids they are faster than S waves

Question 48

what are the properties of S waves?

Answer 48

they are transverse they can only travel through solids

Question 49

why do seismic waves travel in curved paths?

Answer 49

the density changes in the earth

Question 50

what is the area of the earth where S waves cannot be detected?

Answer 50

the S wave shadow zone

Question 51

why is there an S wave shadow zone?

Answer 51

S waves cannot pass through liquids (the liquid outer core!)

Question 52

what causes the P wave shadow zone?

Answer 52

P waves travel faster in solids than they do in liquids this means the P waves slow down as they enter the outer core and refract they also refract when they leave the outer core

Question 53

how did scientists know there was a solid inner core?

Answer 53

faint P waves could be detected in the P wave shadow zones

Question 54

how can the amount of infrared radiation emitted from different surfaces be measured?

Answer 54

using a leslie's cube

Question 55

how can you use a Leslie's cube to investigate infrared radiation?

Answer 55

fill the cube with hot water point the infrared detector at the four surfaces and record the amount of infrared radiation keep the detector at the same distance for each measurement to keep it repeatable

Question 56

list the amount of infrared radiation the surfaces on a Leslie's cube emit from most to least?

Answer 56

matt black shiny black white shiny metallic

Question 57

how do you measure the absorbance of different surfaces of infrared radiation?

Answer 57

use an infrared heater with metal plates on either side each plate has been painted with different surfaces (e.g. matte black on one and shiny on the other) attach a drawing pin with vaseline on to each plate and turn on the heater start timing record the time it takes for the vaseline to melt and the pin to fall off

Question 58

what can happen when waves move from one medium to another?

Answer 58

they can change direction when the change speed

Question 59

what happens when waves slow down?

Answer 59

they bend towards the normal

Question 60

what happens when waves speed up?

Answer 60

they bend away from the normal

Question 61

when do waves not change direction through a medium?

Answer 61

when the waves enter or leave the medium at right angles to the surface

Question 62

what is a wavefront?

Answer 62

an imaginary line which connects the same points on a set of waves

Question 63

why do waves change direction when they enter another medium?

Answer 63

only part of the wavefronts slow down/speed up, causing them to bend towards or away from the normal