SP4 Waves

Question 1

Transverse waves

Answer 1

particles oscillate perpendicular to the direction of wave travel

Question 2

Longitudinal waves

Answer 2

particles oscillate parallel to the direction of wave travel

Question 3

Amplitude

Answer 3

the distance between rest and highest point on a wave

Question 4

Wavelength

Answer 4

distance between a point on a wave and the same point on the next wave

Question 5

Frequency

Answer 5

number of waves passing a point per second, measured in Hz Hertz. = 1/time period

Question 6

Time period

Answer 6

time it takes for a full cycle of the wave to pass a point. = 1/frequency

Question 7

Compression

Answer 7

squashed up particles (lots), high pressure

Question 8

Rarefaction

Answer 8

stretched out particles (fewer), low pressure

Question 9

Velocity

Answer 9

speed of the wave in the direction its travelling

Question 10

Wave speed (m/s) =
v =

Answer 10

distance (m) / time (s)
x / t

Question 11

Wave speed (m/s) =
v =

Answer 11

frequency (Hz) x wavelength (m)
f x λ

Question 12

Options for waves at boundaries

Answer 12

refraction
reflection
absorption
transmission

Question 13

Refraction

Answer 13

the change in direction of a wave when it moves into a different medium

happens at the interface (boundary)

Question 14

Light from medium with low density to high density

Answer 14

slows down, bends towards normal

Question 15

Light from medium with high density to low density

Answer 15

speeds up, bends away from normal

Question 16

Light travelling along the normal

Answer 16

doesn’t change direction between mediums

Question 17

Change in direction in refraction happens because of

Answer 17

change in speed

Question 18

Reflection

Answer 18

the wave bounces off the surface

Question 19

Absorption

Answer 19

the wave disappears as the energy it’s carrying is absorbed by the material

Question 20

Transmission

Answer 20

the wave passes through the material and is not absorbed or reflected

Question 21

As speed changes

Answer 21

the wavelength changes
the frequency stays the sane

Question 22

Path of sound through the ear

Answer 22

1. sound waves enter the ear canal
2. the eardrum is a thin membrane. sound waves make it vibrate
3. vibrations are passed on to tiny bones which amplify the vibrations
4. vibrations are passed on to the cochlea
5. tiny hairs inside the cochlea detect these vibrations and create electrical signals called impulses
6. impulses travel along neurones in the auditory nerve to reach the brain

Question 23

Cochlea and its structure

Answer 23

can detect the different frequencies of sound reaching the ear.

tube shape, made up of fluid and membrane.

membrane is thick at the base, which detects high frequencies, and thin at the apex, which detected low frequencies.

the part of the membrane that vibrates depends on the frequency of the sound waves in the fluid.

hair cells along membrane detect vibrations - each is connected to a neurone that sends impulse to brain

Question 24

Ultrasound

Answer 24

frequencies higher than 20,000 Hz

Question 25

Animal use of ultrasound

Answer 25

use ultrasound waves to listen for echoes that come from the wave reflecting off things around them

Question 26

Human use of ultrasound: sonar

Answer 26

equipment carried on ships/submarines to detect fish and find the depth of the sea (d = s x t)

ultrasound pulses are emitted and reflected by the sea bed

Question 27

Human use of ultrasound: foetal scans

Answer 27

ultrasound scans can be used to make detailed images of unborn babies, to help doctors monitor their health

the probe emits and receives ultrasound waves. a gel is used to stop the ultrasound just reflecting from the skin. the ultrasound machine detects the time between sending the pulse out and receiving the echo. the displays show where the echoes came from. the further down the screen, the longer the echo took to return

Question 28

Infrasound

Answer 28

frequencies less than 20Hz

Question 29

Vibrations caused by earthquakes

Answer 29

Seismic waves

can travel though earth as
longitudinal P waves
transverse S waves

Question 30

P waves

Answer 30

longitudinal

can travel trhough liquids and solids

Question 31

S waves

Answer 31

transverse

can’t travel trhough liquid

Question 32

Structure of earth’s core

Answer 32

crust
mantle
liquid outer core
solid inner core

Question 33

Shadow zone

Answer 33

where S waves can’t be detected

P waves have one too, created by liquid outer core. some weak P waves can be detected in SZ shows that some of the waves must be reflecting off solid inner core