Topic P6 Waves

Question 1

how do waves transfer energy

Answer 1

from one place to another without transferring any matter

Question 2

what is amplitude of a wave

Answer 2

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

Question 3

what is the wavelength

Answer 3

the distance between the same point on 2 adjacent waves

Question 4

what is the frequency

Answer 4

the number of complete waves passing a certain point per second

Question 5

what is frequency measured in

Answer 5

hertz (Hz)

Question 6

what is period measured in

Answer 6

seconds

Question 7

what are transvervse waves

Answer 7

-have sideways vibrations
-they’re perpendicular at the direction of energy transfer

Question 7

waves are either

Answer 7

-transvervse
-longitudinal

Question 8

state which waves are transvervse

Answer 8

1. electromagnetic waves
2. ripples and waves in water
3. a wave on a string

Question 9

what are longitudinal waves

Answer 9

-oscillations are parallel to the direction of energy transfer

Question 9

an example of a longitduinal wave

Answer 9

-air

Question 10

what is wave speed measured in

Answer 10

m/s

Question 11

what is wavelength measured in

Answer 11

metres

Question 12

what should you use an oscilloscope to measure

Answer 12

-to measure the speed of sound
1. set it up so detected waves are shown as seperate waves
2. both microscopes next to the speaker and then slowly move 1 away until next waves are aligned
3. measure distance between the microphones to find 1wavelength

Question 13

state what happens when waves meet boundaries

Answer 13

1. absorbed by 2nd material
2. **transmit **through 2nd material
3. wave is **reflected **

Question 14

what type of waves are electromagnetic

Answer 14

transverse
-they transfer energy from a source to an absorber

Question 15

how does a camp fire transfer energy

Answer 15

-by emitting infared radiation
-they are then absorbed by objects to the thermal energy store

Question 15

how do radio waves transfer energy

Answer 15

to the kinetic energy stores of electrons in radio receivers which generates an electrical current

Question 15

state characteristics of electromagnetic waves

Answer 15

-all travel at the same speed through air
-aren’t vibrations of particles and are vibrations of electric and magnetic fields means TRAVEL THROUGH VACUUM
-vary in wavelength

Question 16

what is refraction

Answer 16

where waves change direction at a boundary

Question 16

state how u detect refraction

Answer 16

when a wave hits the boundary at an angle and changes direction

Question 16

how ray diagrams show the path of a wave

Answer 16

-straight lines that are perpendicular to wave fronts and they show the direction a wave is travelling in

Question 16

state how refracted waves slow down or speed up

Answer 16

-when the waves bends towards the normal, it slows down
-when it bends away from the normal it speeds up

Question 17

how to construct a ray diagram

Answer 17

for a refracted light ray

Question 18

learn how to do a ray diagram

Question 19

how are radio waves made

Answer 19

by oscillating charges -alternating currents are made up of oscillating charges

Question 20

what are radio waves mainly used

Answer 20

for communication

Question 21

how are microwaves used by satellites

Answer 21

-communication to and from satellites use microwaves -its best to use microwaves which can pass easily through the Earth's watery atmosphere -the signal from a transmitter is transmitted into space -the receiver dish orbits thousands of km above earth -satelite transmits the signals back to earth

Question 22

explain how microwave ovens use microwaves

Answer 22

-in microwave ovens the microwaves are absorbed by water molecules in food -the microwave penetrates up a few cm into the food before being absoorbed and transferring the energy -water molecules then transfer energy to the rest of molecules in food by heating, quickly cooking food

Question 23

how can infrared radiation be used to increase temperatures

Answer 23

-infrared cameras are used to detect infrared radiation and monitor temperature -the camera detects the IR radiation and turns it into an electrical signal which is displayed on a screen -the hotter the object is the birghter it appears

Question 24

explain how electric heaters heat a room

Answer 24

-they contain a long piece of wire that heats up when a current flows through it -wire then emits infared radiation -this is then absorbed by objects and energys transferred by the IR waves to thermal energy stores

Question 25

what does fibre optic cables use

Answer 25

visible light to transmit data -they carry data from telephoes over long distances as pulses of visible light -work bc of reflection

Question 26

what are ultraviolet radiation used for

Answer 26

-gives you a suntan -fluorescent lights generate UV radiation which is then re-emitted as visible light by phosphor on the inside of a bulb -energy efficient and are good to use when light is needed

Question 27

state why we use X rays

Answer 27

-for medicine -they pass easily through flesh but not as easily through dense materials like bones or metal

Question 28

what are radiographers used for

Answer 28

-X rays and gamma rays to treat people with cancer

Question 29

state the dangers of using electromagnetic radiation

Answer 29

-they enter living tissues, and is often harmless but sometimes creates havoc -UV radiation damages surface cells, leading to sub burn and can cause blindness and an increased risk of skin cancer -high fequency waves like UV transfer lots of energy + cause lots of damage

Question 30

state how to measure risks by using radiation doses in sieverts

Answer 30

-by radiation doses, which is measured in sieverts