Waves (6) -pt1

Question 1

What can waves only travel through?

Answer 1

A medium, because they need the particles to transpercer the energy

Question 2

What’s the amplitude of a wave?

Answer 2

The amplitude of a wave is the maximum displacement of a point on a wave away from its undisturbed position.
(The height)

Question 3

What’s the wavelength of a wave?

Answer 3

The wavelength of a wave is the distance from a point on one wave to the equivalent point on the adjacent wave.

Question 4

What’s the frequency of a wave?

Answer 4

The frequency of a wave is the number of waves passing a point each second.
measured in Hz
1Hz is 1 wave per second

Question 5

What’s the formula to find a period?

Answer 5

Period (s) = 1 / frequency (Hz)

T = 1 / f

Question 6

What are the two types of waves?

Answer 6

Transverse or longitudinal

Question 7

What are the properties of a transverse wave?

Answer 7

• the oscillations are perpendicular to the direction of energy transfer
• eg. All electromagnetic waves (light), water waves

Question 8

What are the properties of a longitudinal wave?

Answer 8

• the oscillations are parallel to the direction of energy transfer
• it’s a series of compressions and rare fractions
• eg. Shock waves, sound waves

Question 9

What’s wave speed and what formula can you use to calculate it?

Answer 9

-the speed which energy is transferred at
Wave speed (m/s) =frequency (Hz) x wavelength (m)

Question 10

What are mechanical waves?

Answer 10

Waves that can be both longitudinal and transverse

Question 11

What are oscilloscopes used for?

Answer 11

To measure the speed of sound

Question 12

When a wave arrives at a boundary between 2 different materials what happens? And why?

Answer 12

-it can be absorbed by the new material-transferring energy to a materials energy stores
-they’re transmitted-they carry on traveling through the new material (often leads to refraction)
-the wave if reflected
(What happens depend on the wavelength and the properties of the material involved)

Question 13

Angle of incidence =

Answer 13

Angle of reflection

Question 14

Where’s the angle of incidence? And what’s the normal?

Answer 14

• it’s the angle between the incoming wave and the normal
• normal is draw an a dotted line. It’s perpendicular to the surface at the point of incidence, which is where the wave hits the boundary

Question 15

What’s the angle of reflection?

Answer 15

-the angle between the reflected wave and the normal

Question 16

What’s specular reflection?

Answer 16

• it happens when a wave is reflected in a single direction by a smooth surface
• eg. When light is reflected by a mirror you get a clear reflection

Question 17

What’s diffuse reflection?

Answer 17

• it’s when a wave is reflected by a rough surface and the reflected rays are scattered in lots of different directions (I still =R)
• this happens because the normal is different for each Ray so the an,e if incidence is different for each ray
• when light is reflected from a rough surface it appears matte and you don’t get a clear reflection. eg. A piece of paper

Question 18

What’s are the properties of EM waves?

Answer 18

• transverse waves. transfer energy from a source to absorber
• they can travel through vacuums because they’re not vibrations of particles but vibrations electric and magnetic fields
• all travel at the same speed
• a variety changes in the atoms and nuclei cause EM waves to have such a large range of frequencies

Question 19

What are the 7 EM waves in order of longest wave length and lowest frequency first?

Answer 19

• radio waves 1m - 10*4m
• micro waves 10*-2m
• infra red 10*-5m
• visible light 10*-7m
• ultra violet 10*-8m
• x-rays 10*-10m
• gamma rays 10*-15m

Question 20

What’s refraction?

Answer 20

When a wave crosses a boundary between 2 materials at an angle and changes directions

Question 21

How much a wave refracts depends on what?

Answer 21

• how much the wave speeds up or slows down
• which depends on the density of the 2 materials (the higher the density the slower the wave)
• if it slows down it bends towards the normal
• if it speeds up it bends away from the normal

Question 22

What happens when a wave refracts?

Answer 22

-the wavelength of the wave changes but the frequency stays the same

Question 23

What happens when a wave is travelling long the normal (a straight line) when it crosses the boundary into a different material?

Answer 23

-it will change speed but it’s not refracted

Question 24

What’s optical density?

Answer 24

• A measure of how quickly light can travel through a material
• the higher the optical density, the slower light waves travel through it

Question 25

How are radio waves produced?

Answer 25

by oscillations in electrical circuits.

Question 26

Why are radio waves absorbed ?

Answer 26

• When radio waves are absorbed they may create an alternating current with the same frequency as the radio wave itself
• so radio waves can induce oscillations in an electrical circuit.

Question 27

How do long-wave radio signals work?

Answer 27

• they can travel halfway round the world
• due to the long wavelengths that can diffract around the curved surface of the earth
• also diffract around hills, into tunnels, etc
• so radio waves can received even if the receiver isn’t in line in sight of the transmitter

Question 28

How do short-radio signals work?

Answer 28

• like long-wave signals it can be revived by long distances

- this is because they are reflected from the ionosphere

Question 29

How do TV and FM radio transmission work?

Answer 29

• they have very short wavelengths

- to get reception you must be in direct sight of the transmitter

Question 30

What are radio waves used for?

Answer 30

radio waves – television and radio