WAVES

Question 1

Waves transfer ______ in the ___________ they are _______

Answer 1

waves transfer energy in the direction they are travelling

Question 2

what is the amplitude of a wave

Answer 2

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

Question 3

what is the wavelength of a wave

Answer 3

is the distance between the same point on two adjacent waves

Question 4

what is the frequency of the wave

Answer 4

is the number of complete waves passing a certain per second

Question 5

what is frequency measured in

Answer 5

hertz

Question 6

what is the equation for the period of a wave

Answer 6

T=1/F
T= PERIOD
F=FREQUENCY

Question 7

THE TWO TYPES OF WAVES

Answer 7

transverse and longitudinal

Question 8

in transverse waves….

Answer 8

the oscillations are perpendicular to the direction of energy transfer

Question 9

examples of transverse waves

Answer 9

all electromagnetic waves
waves in water
a wave on a string

Question 10

in longitudinal waves

Answer 10

the oscillations are parallel to the direction of energy transfer

Question 11

examples of longitudinal waves

Answer 11

sound waves

shock waves

Question 12

equation for wave speed

Answer 12

frequency * wavelength

Question 13

waves can be….

Answer 13

absorbed, transmitted or reflected

Question 14

angle of incidence =

Answer 14

angle of reflection

Question 15

what is specular reflection

Answer 15

specular reflection is when a wave is reflected in a single direction by a smooth surface

Question 16

what is diffuse reflection

Answer 16

is when a wave is reflected by a rough surface and the reflected rays are scattered in lots of different directions

Question 17

all EM waves are…

Answer 17

transverse waves

Question 18

all EM waves travel…

Answer 18

at the same speed through air or a vacuum

Question 19

WHEN a wave crosses a boundary between materials at an angle

Answer 19

it changes direction

Question 20

what depends on how much a wave is refracted

Answer 20

how much the wave speeds up or slows down

and density

Question 21

the higher the density

Answer 21

the slower the wave travels through the material

Question 22

what is refraction

Answer 22

when waves change direction at a boundary

Question 23

what happens if a wave crosses a boundary and it slows down

Answer 23

it bends towards the normal

Question 24

what happens if a wave crosses a boundary and it speeds up

Answer 24

it will bend away from the normal

Question 25

how can you produce radio waves

Answer 25

using an alternating current in an electrical circuit

Question 26

what are radio waves used for

Answer 26

are mainly used for communication radios tvs

Question 27

what are microwaves used for

Answer 27

microwaves are used for communication to and from satellites heating food

Question 28

what is infrared radiation used for

Answer 28

infrared cameras | increase or monitor temperature

Question 29

explain why signals between satellites are transmitted as microwaves

Answer 29

because they can pass through the earth atmosphere

Question 30

what is given out by all hot objects

Answer 30

infrared radiation

Question 31

uses of visible light

Answer 31

fibre optic cables to transmit data

Question 32

how do fibre optic cables work

Answer 32

they work because of reflection. the light rays are bounced back and forth until they reach the end of the fibre

Question 33

uses of UV

Answer 33

UV pens | sun tanning

Question 34

uses of xrays and gamma rays

Answer 34

they are used in medicine xrays are used to see if people have broken bones both used to treat people with cancer gamma can be used as a medical tracer

Question 35

how do radiographers use xrays and gamma rays to treat people with cancer

Answer 35

these rays can kill the cancer cells

Question 36

how is gamma radiation used in a medical tracer

Answer 36

a gamma emitting source is injected into the patient and its progress is followed around the body gamma radiation is used as can pass out of the body to be detected

Question 37

how do you get an xray image

Answer 37

xrays pass easily through flesh but not so easily through bone. the amount of radiation absorbed gives you the xray image

Question 38

what do radiographers wear to protect themselves from radiation

Answer 38

lead aprons

Question 39

what is the electromagnetic specttrum

Answer 39

``` radio waves microwaves infrared radiation visible light ultraviolet xrays gammarays ```

Question 40

as you go down the electromagnetic spectrum

Answer 40

the wavelength decreases | the frequency increases

Question 41

what are the ionising ones in the EM spectrum

Answer 41

UV gamma xrays

Question 42

why are low frequency waves less harmful

Answer 42

they don't transfer much energy and so mostly pass through soft tissue without being absorbed

Question 43

why are high frequency waves dangerous

Answer 43

they all transfer lots of energy and so can cause lots of damage

Question 44

why is uv radiation dangerous

Answer 44

damage surface cells which can lead to sunburn | increased risk of skin cancer

Question 45

why are xrays and gamma rays dangerous

Answer 45

types of ionising radiation can cause gene mutation or cell destruction cancer

Question 46

how do lenses form images

Answer 46

by refracting light and changing its direction

Question 47

WHAt are the two main types of lens

Answer 47

concave and convex

Question 48

what is a convex lens

Answer 48

a convex lens bulges outwards it causes rays of light parallel to the axis to be brought together at the principal focus

Question 49

what is a concave lens

Answer 49

a concave lens caves inwards. It causes parallel rays of light to spread out

Question 50

what is the principal focus of a convex lens

Answer 50

is where rays hitting the lens parallel to the axis all meet

Question 51

what is the principal focus of a concave lens

Answer 51

is the point where rays hitting the lens parallel to the axis appear to come from

Question 52

to describe an image properly what do you need to say

Answer 52

how big it is compared to the object real or virtual upright or inverted

Question 53

how would you draw a ray diagram through a conc=vex lens

Answer 53

draw a ray from the top of the object to the lens draw a ray from the top of the object through the middle of the lens the ray that has touched the lens should be refracted through the focal point the ray that goes through the middle of the lens should be extended where the rays meet is the image

Question 54

what should you always remember when you draw rays

Answer 54

arrows on the rays

Question 55

an object at 2f will produce....

Answer 55

a real, inverted image the same size as the object and it is at 2f

Question 56

an object between f and 2f will produce...

Answer 56

a real inverted image bigger than the object and beyond 2f

Question 57

an object nearer than f will produce..

Answer 57

a virtual image the right way up bigger than the object and the same side of the lens

Question 58

concave lenses always produce a

Answer 58

virtual image

Question 59

magnification=

Answer 59

image height/object height