P6 Waves Flashcards

1
Q

What is wavelength

A

The distance from a point on a wave to the equivalent point on. The adjacent one. Measured in meters

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2
Q

What is amplitude?

A

The maximum displacement of a point on a wave away from its undisturbed position.

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3
Q

What is frequency?

A

The number of complete waves that pass a point in 1 second.

Measured in Hertz

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4
Q

What is time period?

A

The time to complete one wavelength

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5
Q

What is a transverse wave?

A

Particles are at right angles to the direction of the energy transfer. Move up & down. Eg. Water waves

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6
Q

What is a longitudinal wave?

A

The vibrations of the particles are parallel to the direction of energy transfer. Move left & right

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7
Q

What is compression

A

Where the particles are closer together

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8
Q

What is rarefaction

A

When the particles are spread out.

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9
Q

Sound waves

A

They are longitudinal.

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10
Q

Change in speed of sound waves

A

When a sound is transmitted across a boundary from one medium to another, it’s speed changes.( frequency stays the same and wavelength changes)

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11
Q

Electromagnetic waves

A

Microwaves- transfers data to mobile phones
Electric fire- transfers infrared waves to heat us up
Ultraviolet- transferred from the sun
X-Ray machine -transfers X-rays which some of is absorbed by the body.
Radioactive sources- transfer gamma rays

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12
Q

What is an echo?

A

A reflected sound

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13
Q

Echo sounding

A

Animals can hear higher frequencies than us. Bats emit pulses of 20000Hz to 100000Hz.
Ships use high frequency sounds to find the depth of the seabed or to locate a shoal of fish.

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14
Q

What is the human sound range?

A

20Hz to 20KHz

Anything above 20KHz are considered ultrasounds

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15
Q

RP: measuring the wavelength and speed in a ripple tank and waves in a solid.

A

Use a ripple tank to measure/calculate wavelength and frequency then work out speed.
Use a mechanical vibrator to vibrate a stretched string. To produce a transverse wave. Once the wave is travelling at a steady speed count the wavelength and frequency then calumet the speed.

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16
Q

What is a ray diagram?

A

Model that shows the number of lines (rays) travelling in a straight line between the wave source and an object or surface. The arrow on the ray shows the direction it is traveling in.
Incident Ray is the one going to the surface and the rejection Ray is the one going away from the surface

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17
Q

What happens when a wave meets a boundary?

A

It is either reflected, absorbed or transmitted

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18
Q

Law of reflection

A

When a wave is reflected off a surface, the angle of incidence is equal to the angle of reflection

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19
Q

What is refraction

A

When a wave changes direction & speed when it enters a different medium.

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20
Q

RP: investigate the reflection of light by different types of surface and the refraction of light by different substances

A

Specular reflection- all light rays reflected at the same angle
Diffuse reflection- light from one direction is reflected at many different angles.
When light rays enter a denser material, it bends towards the normal.
The angle of reflection should be the same as the angle of refraction.

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21
Q

Speed of sound in different media

A

Solids are dense so sound travels the quickest in them as the particles are closely packed together.

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22
Q

Uses of ultrasound

A

Industrial- find cracks/ gaps in aircrafts & measure thickness of objects
Medical- body scans (babies in the womb), measure speed of blood flow in a vein or artery

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23
Q

Why do we use ultra sounds instead of X-rays

A

Safety- ultrasounds are safe, X-rays are ionising radiation
Imaging- X-rays have high penetrating power so travel through soft tissue, ultrasounds reflect off soft tissue to produce an image

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24
Q

Why do we use gel?

A

Gel creates a similar frequency so the ultrasound can pass through the skin to get a reflection from soft tissue

25
Q

What do we use to measure seismic waves?

A

A seismometers

26
Q

What are P waves

A

Is a primary (pressure wave)
Longitudinal waves similar to a sound wave
Speed generally increases with depth in the earth
Can travel through solids and liquids
Slower in liquids than in solids

27
Q

What is an S wave?

A
Secondary (shear wave)
Transverse wave
Speed generally increases with depth in the earth
Slower than P waves
Can not travel through liquids
28
Q

P wave shadows zones

A

Travel through both solids and liquids. As they move through each area, waves are refracted at each layers to create shadow zones

29
Q

S wave shadow zones

A

S waves only pass through solids and can not be refracted through the core. Therefore a greater shadow zone is created.

30
Q

Electromagnetic waves

A

Are transverse waves

All travel at the speed of light of 3.0 X 10 to the power of 8

31
Q

Electromagnetic spectrum

A
Radio waves- longest wavelength 
Microwaves
Infrared radiation 
Visible light
Ultraviolet 
X-rays
Gamma rays- highest frequency and energy
32
Q

What will happen if you put foil behind a radiator?

A

Thermal energy will be reflected back. Keeping your house warmer

33
Q

Refraction of electromagnetic waves

A

Can be refracted when they enter a medium in which the wave velocity is different. Shorter the wavelength, more the wav refracted.
Amount of refraction can be affected by differences in the atmospheric temperature and pressure.

34
Q

What is wavefront?

A

A line that joins all the points on a wave which are moving up and down together at the same time. The wavefront is at right angles to the direction the wave is travelling in.

35
Q

What are X-rays

A

They have short wavelengths between 0.1 and 10nm.
Created when high energy electrons suddenly loose energy.
Produced artificially using a X-ray tube

36
Q

What are X-rays used for?

A

Imaging- medical and industrial
Security
Treating cancer

37
Q

Gamma rays

A

Wavelength between 0.001 and 0.1 nm

38
Q

What are the uses of gamma rays?

A

Medical (tracers)
Sterilising food and equipment
Treating cancer (gamma knife)
Industrial imaging

39
Q

Ultraviolet radiation

A

Wavelength ranges between 10 to 1000nm
We can’t see it but some animals can
Emitted from the sun

40
Q

Uses of ultraviolet radiation

A

Bright clothing- certain chemicals absorb uv radiation and emit it as visible light (high vis)
Security marking- special inks only viable in UV light
Tanning
Helps the skin make vitamin D

41
Q

Protection from UV light

A
Cover up
Stay in the shade
Wear a wide brimmed hat
Sunglasses 
Wear sun cream
42
Q

RP: investigate the amount of infrared radiation absorbed or radiated by a surface depends on the nature of that surface

A

Have cube with hot water in it see which surface emits the most radiation using sensors. Also see which surface absorbs the most radiation
The darker and duller the material the better it is at aborning and emitting infrared radiation

43
Q

Properties of microwaves

A

Radio waves with shorter wavelengths
Wavelength= 1mm to 30cm
Less energy with phones than with cooking

44
Q

Cooking with microwaves

A

Don’t use flame or heated metal
Quicker and cheaper
Penetrated 1cm into outer layers before being absorbed
Energy transfer makes fat and water molecules vibrate faster
Energy is then transferred from water and fat molecules to centre of the food by conduction

45
Q

Radar

A

Uses microwaves to pass through the atmosphere and is reflected back to detect objects in the way of the aircraft

46
Q

What is an object that transmits light?

A

Transparent or translucent

Opaque objects don’t let light through

47
Q

How is the colour of an object determined?

A

Light can either be aborted or reflected
In a black object all the light is absorbed
In a white object all the light is reflected
In a red object all the light is absorbed apart from the red light which is reflected etc.

48
Q

Effect of colour filters

A

Colour filters work by absorbing certain wavelength (colours) and transmitting other wavelengths

49
Q

Convex lens

A

Lens is narrow at the purposive and bulges in the middle

50
Q

Concave lens

A

Lens is narrow in the middle and the widest at the outside

51
Q

Principle axis

A

The horizontal line going through the centre of a lens

52
Q

Principle focus

A

Light rays are travelling parallel to the principle axis of a convex lens are refracted to pass through the focus and the light rays are focuses at that point

53
Q

Real image

A

Formed by the actual intersection of rays so it can be seen on a screen or other surface placed at the point of intersection

54
Q

Focal length

A

The distance from the optical centre of the lens to the focal point/ principle focus

55
Q

Forming a real image

A

1 draw a Ray from the object, parallel to the principal axis which refracts through the principal focus (on the other side of the lens)
2 draw a Ray from the object through the optical centre of the lens. This Ray does not change direction.
3 it is helpful to draw a third Ray to confirm the position of the image. Draw a Ray from the object through the principal focus infront of the lens to the lens and then parallel to the principal axis

56
Q

A perfect black body

A

An object that absorbs all the radiation that falls onto it. It is also the best emitter of radiation.

57
Q

Temperature of the earth

A

Energy entering the earths atmosphere have a shorter wavelength so are more penetrating.
The earth emits radiation as its temperature is higher than that of its surroundings. Although they have a longer wavelength and are less penetrating so some is reflected back to Earth by the atmosphere.

58
Q

3 main greenhouse gases

A

Carbon dioxide
Methane
Nitrogen

59
Q

Changing the earths radiation balance

A

Changes in human activity

Eg. Burning less fossil fuels & preventing deforestation