p5

Question 1

waves

Answer 1

transfer energy from one place to another (doesnt transfer any matter)

Question 2

displacement

Answer 2

how far wave has oscillated from equilibrium point

Question 3

amplitude

Answer 3

distance between trough and middle or crest and middle

Question 4

wavelength

Answer 4

distance of one entire oscillation

Question 5

time period

Answer 5

time it takes for one oscillation

Question 6

transverse waves

Answer 6

oscillations perpendicular to direction of energy transfer

electromagnetic waves
ripples/ waves in water
waves in strings

Question 7

longitudinal waves

Answer 7

oscillations parallel to direction of energy transfer

sound waves
seismic p-waves

Question 8

waves can be

Answer 8

absorbed - energy from wave transferred to that materials energy stores
transmitted - enters material but carry on travels, passed out other side, often leads to refraction
reflected - doesnt enter material

what happens depend on wavelength and properties of materials

Question 9

ray diagrams

Answer 9

show reflection
angle of incident = angle of reflection

Question 10

boundary is flat

Answer 10

normals are in same direction as surface is flat
all incoming light rays reflected in same direction
specular reflection - clear image, like mirror

Question 11

boundary is bumpy

Answer 11

normals are in different directions as surface isnt flat
light reflected in different directions
diffuse/scattered reflection - cant see reflection, like paper

Question 12

refraction

Answer 12

waves change direction as they pass from one medium to another

frequency always stays the same, only wave speed and length change

Question 13

why do waves travel at speeds

Answer 13

waves travel at different speeds in different mediums as mediums have different density

Question 14

how does density affect speed

Answer 14

higher density = slower speed
if refracted, it will bend towards normal

Question 15

when does refraction happen

Answer 15

if light wave hits boundary at angle, it will be refracted - direction will change

Question 16

concave

Answer 16

light rays diverge
wider ends, thinner centre
image will always be virtual

Question 17

convex

Answer 17

light rays converge
thinner ends, wider centre

Question 18

soumdwaves

Answer 18

vibrations that pass through molecules of a medium
longitudinal wave
travel as series of compressions and rarefactions

Question 19

compressions

Answer 19

particles closest together

Question 20

rarefactions

Answer 20

particles furthest apart

Question 21

soundwaves travelling through solids

Answer 21

cause particles in solid to vibrate
vibrating particles collide with neighbour and pass on vibration
happens over and over again
soundwave transmitted

Question 22

how does density of particles affect soundwaves

Answer 22

soundwaves need particles to transmit sound
more densely packed - faster sound travelled
this is why sound travels fastest in solids and slowest in liquids and cant travel in vacuum

Question 23

soundwaves frequency

Answer 23

frequency doesnt change
wavelength gets longer as sound speeds in high density materials
wavelength gets shorter as sound slows down in low density materials such as air

Question 24

human hearing

Answer 24

1. The outer ear collects the sound which travels into the ear.
2. The sound waves cause the eardrum to vibrate at the same frequency.
3. This is amplified by three ossicles (small bones). ]
4. This causes the hair in the cochlea to vibrate.
5. The cochlea converts the vibrations into electrical signals.
6. The signals are passed to brain through the auditory nerve.
7. The brain converts the electrical signals into sound.

Question 25

ultrasound

Answer 25

sound that vibrates at frequencies above 20,000 hz ultrasound wave travels through an object, but every time it hits a boundary, some waves reflected back. if we know the speed of sound wave and time taken to be relflected, we can work out how far away boundary is. we can repeat this to see the internal structure completely safe

Question 26

ultrasound machine

Answer 26

ultrasound device - transmit and receive ultrasound waves scans foetuses place us device on pregant belly ultrasound waves pass through stomach towards fetus everytime they pass through different mediums (tissue and fluid, etc) , some waves reflected back, timing and distance used to calculate images of foetus

Question 27

check quality

Answer 27

ultrasound checks quality of products in industry fire ultrasound waves at object - should be completely solid waves should go straight through and only be partially reflected at start of object and end ( at the boundaries) if theres a crack, will be reflected back at the crack so company can tell theres a fault

Question 28

echosounding

Answer 28

boats and sumbarines fire ultrasounds at sea floor or other objects to see how far way they are sends ultrasounds and certain speed and gets time for how long it took for wave to be reflected, distance can be calculated.

Question 29

electromagnetic waves

Answer 29

all transverse waves in a vacuum they all travel at same speed - 3x10^8 in diff mediums they travel at diff speeds - can lead to refraction come from everywehre

Question 30

electomagnetic spectrum

Answer 30

wavelength and frequency inversely related r-g wavelength decreases rich men in vegas use expensive girls

Question 31

what can people see

Answer 31

visible light red orange yellow green blue indigo violet

Question 32

ultra-violet, x-rays, gamma rays

Answer 32

ionising - cause damage to cells

Question 33

radiowaves, microwaves

Answer 33

used for communcation

Question 34

gamma rays

Answer 34

emitted from radioactive decay

Question 35

visible light, ultra-violet,x-rays

Answer 35

emitted when electrons drop down energy level

Question 36

infrared

Answer 36

emitted when bonds holding molecules together vibrate

Question 37

radiowaves

Answer 37

can be generated from electircity in the form of an alternating current (made up of oscillating currents)

Question 38

process of generating radiowaves

Answer 38

using transmitter connected to oscilloscope - allows us to see frequncy of alternating current, which determines the frequency of wave produced once radiowave generated, we can use reciever which aborbs energy and generates a.c

Question 39

main use of radiowaves

Answer 39

for communication - long waves short waves very short waves

Question 40

microwaves

Answer 40

absored by water molecules - microwave ovens, most food we eat has lots of water molecules, energy of waves absorbed by water molecules and transfer energy to neighbours so heat spreads throughout food arent absorbed - used for communication in satellites as they have to pass through earths atmosphere ( cant do if abosrobed by water molecules )

Question 41

infrared

Answer 41

emitted from all objects that have thermal energy hotter object - more infrared rsdiation emitted infrared cameras to spot living organisms - we can see hot and cold areas, showing animals as bright as they emit lots of infrared rared cooking - makes metal emit lots of infraed which heats food by transfering heat energy infrared radiation doesnt penetrate food

Question 42

visible light

Answer 42

light we use to see diff colour depending on wave length red has longest wave length, violet has shortest communication using optical fibres - can transmit pulses of light over long distances - light is reflected every time it hits surface, so bounces up and down need to use materials that will totally reflect light can use copper wires, however transmits less data + more likely to be distorted

Question 43

ultraviolet

Answer 43

ultraviolet radiation emitted from sun can be generated from sun beds

Question 44

fluroescence

Answer 44

uv light is absorbed, energy re-emitted as visible light

Question 45

fluroscent lights

Answer 45

generates uv radiation absorbed by a layer of phosphorus re-emits light as

Question 46

security

Answer 46

security pens completely invisible until we shine uv light on them

Question 47

sterilise water

Answer 47

uv radiation kills microorgaisms

Question 48

x-rays

Answer 48

view internal structure of objects x-rays absorbed by dense materials, move past parts that are mostly air and partly through fleshy parts