P6-waves

Question 1

what is the direction of the oscillations in transverse waves?

Answer 1

they are perpendicular to the direction of energy transfer

Question 2

give three examples of transverse waves:

Answer 2

light waves, ripples in water, a wave on a string ( like on a guitar)

Question 3

what direction are the oscillations of a longitudinal wave?

Answer 3

they are parallel to the direction of energy transfer

Question 4

give two examples of longitudinal waves:

Answer 4

sound waves in air
shock waves (e.g seismic waves)

Question 5

how do waves transfer energy?

Answer 5

When waves travel through a medium,the particles of the medium oscillate, transferring energy between each other. (particles stay in the same place though)

Question 6

what is the amplitude of a wave?

Answer 6

the max. displacement of a point on the wave from it’s undisturbed position.

Question 7

what is the wavelength of a wave?

Answer 7

the distance between the same point on two adjacent waves.

Question 8

what is the frequency of a wave?

Answer 8

the number of complete waves passing a certain point per second. measured in Hz

Question 9

what is 1Hz equal to?

Answer 9

1 wave per second

Question 10

what is the equation linking frequency, wave speed and wavelength?

Answer 10

wave speed (m/s)= frequency (Hz) x wavelength (m)

Question 11

when are waves refracted?

Answer 11

when a wave crosses a boundary at an angle, it’s direction gets changed.

Question 12

what determines how much a wave is refracted?

Answer 12

How much the wave speeds up/slows down . This depends on the density of the material

Question 13

what happens to a wave that slows down when it crosses the boundary?

Answer 13

It bends towards the normal.

Question 14

what happens to a wave that speeds up as it crosses a boundary?

Answer 14

it bends away from the normal

Question 15

what changes and what stays the same when a wave is refracted?

Answer 15

the wavelength changes, the frequency stays the same.

Question 16

what is the optical density of a material?

Answer 16

a measure of how quickly light can travel through it. Higher optical density-light waves travel slower.

Question 17

Drawing a ray diagram for refraction:
draw in the __________between 2 materials, and the _______
draw an _____ ray which meets the normal at the boundary. the < between the ray and the normal is the angle of _________.
now draw the ________ray . the angle of refraction depends on the _______ of the material.

Answer 17

boundary, normal. Incident, incidence.refracted, optically dense.

Question 18

radio waves are apart of…?

Answer 18

the electromagnetic spectrum. EM waves are made up of oscillating electric and magnetic fields.

Question 19

radio waves travel at the speed of what?

Answer 19

light

Question 20

are radio waves transverse or longitudinal?

Answer 20

transverse.

Question 21

can radio waves travel through a vacuum?

Answer 21

yes

Question 22

give three examples of signals that radio waves carry:

Answer 22

Tv, radio and mobile phone signals

Question 23

give another use of radio waves:

Answer 23

they can wirelessly connect a computer to a printer. Bluetooth

Question 24

State three properties of short length radio waves:

Answer 24

they carry more information
they have a shorter range
they spread out less ( they don’t weaken as much)

Question 25

what are radio wave lengths of less than 1 metre used for and why?

Answer 25

they are used for TV broadcasting from TV masts. This is because they carry a lot of information.

Question 26

what are radio waves of length 1m-100m used for and why?

Answer 26

local radio stations, emergency services. they have a short range.

Question 27

what are radio waves length greater than 100 m used for?

Answer 27

national/international radio stations. They have a longer range.

Question 28

what is different about how long length radio waves compared to short ones?

Answer 28

Long waves diffract around the curved surface of the earth.They can diffract around hills and into tunnels. Whereas short wavelengths are reflected from the ionosphere

Question 29

transmitting and receiving radio waves: 1-microphone produces an_______ ______ 2-this causes_____to oscillate in _______ aerial 3-the aerial emits ______ waves 4-the waves are absorbed by ______ aerial 5- electrons_____ in the receiver, generating an _______ current with the same _______ as radio waves.

Answer 29

``` alternating current electrons, transmitter radio receiver oscillate, alternating frequency ```

Question 30

if you can’t hear radio waves, how can radios produce the noise from the waves?

Answer 30

radio waves carry signals which the receiver converts into sound waves.

Question 31

How do lenses work?

Answer 31

they refract light and change it’s direction.

Question 32

what are the two types of lens?

Answer 32

concave and convex.

Question 33

what is the shape of a convex lens and how does it refract light?

Answer 33

It bulges outwards () . Rays of light parallel to the axis are brought together and converge at the principal focus.

Question 34

what is the shape of a concave lens and how does it refract light?

Answer 34

it caves inwards )(. rays of light parallel to the axis diverge.

Question 35

what is the axis of a lens?

Answer 35

a line passing through the middle of the lens

Question 36

what is the principal focus of a convex lens?

Answer 36

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

Question 37

what is the principal focus of a concave lens?

Answer 37

where all the rays hitting the lens parallel to the axis APPEAR to all come from (they can be traced back until they all appear to meet up at a point behind the lens)

Question 38

what is the focal length?

Answer 38

the distance from the centre of the lens to the principal focus (there’s a principal focus on either side of the lens)

Question 39

what are the three rules of convex lenses?

Answer 39

1-an incident ray parallel to the axis refracts through the lens and passes through the principal focus on the other side 2-an Incident ray passing through the principal focus will refract through the lens and travel parallel to the axis 3-an incident ray traveling through the centre of of the lens carried on in the same direction.

Question 40

what are the three rules for concave lenses?

Answer 40

1-An incident ray parallel to the axis will refract through lens and travel in line with the principal focus 2-an incident ray travelling through lens towards principal focus will refract and travel parallel to the axis 3-incident ray passing through centre carries on in same direction

Question 41

what is a real image and give an example:

Answer 41

the light from an object comes together to form an ‘image on a screen’. Eg the image formed on an eye’s retina.

Question 42

what is a virtual image? give an example

Answer 42

where rays are diverging so light appears to be coming from somewhere else. Eg a mirror. you can use a magnifying glass to get a virtual image.

Question 43

what three things are needed to describe an image?

Answer 43

1-size compared to object 2-if it’s upright or inverted compared to object 3-of its real or virtual

Question 44

will a concave lens always give a real or virtual image?

Answer 44

virtual