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National 4/5, Waves and radiation, physics > Waves and Radiation > Flashcards

Waves and Radiation Flashcards

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1
Q

what do waves transfer from one place to another

A

energy

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2
Q

the particles of the medium carrying the wave move (vibrate at right angles to the direction of travel.
what wave is this talking about

A

transverse wave

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3
Q

what are some examples of transverse waves

A

water waves and electromagnetic waves (eg, light)

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4
Q

the particles of the medium carrying the wave move (vibrate) parallel to the direction of energy travel.
what wave is this talking about

A

longitudinal wave

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5
Q

what is an example of a longitudinal wave

A

sound

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6
Q

what is the definition of period

A

time taken for one wave to pass a point

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7
Q

what is the definition of frequency

A

number of waves passing a point each second

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8
Q

what is the definition of amplitude

A

distance from the mid line to a wave crest or wave trough

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9
Q

what is the definition of wave speed

A

distance the wave travels each second

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10
Q

what does f, N and t mean and what are they measured in

A

frequency of the wave measured in hertz (Hz), number of waves, time (s)

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11
Q

what does T stand for and what is it measured in

A

period of the wave measured in second (s)

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12
Q

what does v, λ and f stand for and what are they measured in

A

speed of wave measured in metres per second (m s-1), wavelength measured in metres (m) and frequency measured in hertz(Hz)

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13
Q

what does v, d and t stand for

A

speed of wave measured in metres per second (m s-1), distance wave travels in metres (m) and time taken for wave to travel given distance(s)

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14
Q

how can sound waves be analysed

A

by connecting a microphone or signal input into a oscilloscope

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15
Q

what happen is the frequency and amplitude of a sound change

A

frequency changes the pitch, amplitude changes the loudness

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16
Q

what happens to the screen of an oscilloscope if you change the frequency or pitch

A

more or less waves will be displayed

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17
Q

what happens to the screen of an oscilloscope if the amplitude or loudness is changed

A

the vertical height changes

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18
Q

what are ultrasound waves

A

waves with the same speed as normal sound waves but they have a higher frequency. if a sound is over 20,000 hertz (above the frequency humans can hear), it is an ultrasound wave

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19
Q

what are the uses of ultrasound

A
  1. cleaning delicate instruments
  2. scanning unborn children in their mother’s womb
  3. detecting cracks or flaws in metal
  4. detecting tumours
  5. measuring blood flow through the heart
  6. detecting kidney stone
  7. sonar devices (boat sends out series of ultrasound pulses and these are reflected back from the sea bed. the depth of water can be calculated from the time between the pulse being sent out and the echo returning)
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20
Q

what is the loudness of a sound measured in

A

decibels (dB)

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21
Q

prolonged exposure to what loudness of a sound will lead to damaged hearing

A

90dB

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22
Q

how can you protect against loud noises

A

ear defenders

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23
Q

what is diffraction and when does it occur and with what type of wave

A

diffraction is when waves hit an object and bend around that object. it can occur with any type of wave, eg water wave, sound wave, or microwave

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24
Q

what can make more diffraction happen

A

a greater wavelength

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25
Q

what will radio waves diffract around

A

an object such as a large building or hill

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26
Q

will short wave, higher frequency broadcasts like television waves, diffract around an object

A

no, they would be blocked by something like a hill, whereas longer wave broadcasts such as radio broadcasts are able to diffract around the hill more

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27
Q

what does the electromagnetic spectrum consist of

A

a family of waves, all of which are

  1. transverse
  2. can travel through a vacuum
  3. travel at 3.0x10 to the power of 8 ms-1 in a vacuum
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28
Q

what type of waves carry the most energy

A

higher frequency waves carry the most energy, therefor gamma radiation is the most dangerous as it has the highest frequency.

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29
Q

what are waves in the electromagnetic scale

A

Rude Men Insult Very Ugly eX Girlfriends

  1. radio and tv waves (low frequency, long wavelength, low energy)
  2. microwave
  3. Infrared
  4. Visible Light (ROYGBIV)
  5. Ultraviolet
  6. X-rays
  7. Gamma (high frequency, short wavelength, high energy)
30
Q

What are sources, detectors and uses for radio and tv waves

A

sources : transmitting aerial (radio mast)
detectors : receiving aerial
uses : - long range communication
- radar

31
Q

What are sources, detectors and uses for microwaves

A

sources : transmitting aerial
detectors : receiving aerial
uses : - mobile phone communication
- heating food

32
Q

What are sources, detectors and uses for infrared

A

sources : sun, IR emitting diode, hot wire
detectors : photodiode, thermocouple, thermometer
uses : - short range communication eg tv remote control
- heal torn muscles
thermograms

33
Q

What are sources, detectors and uses for visible light

A 
sources : sun, light bulb, LED
detectors : photodiode, photovoltaic cells
uses : - endoscope
- lasers
- vaporise tumours
- photovoltaic cells
34
Q

What are sources, detectors and uses for ultraviolet

A 
sources : sun, UV lamp
detectors : photodiode, UV sensitive photographic film
uses : - subbed lamps
- security marking
- help severe acne
- cure jaundice
 - sterilisse medical equipment
35
Q

What are sources, detectors and uses for X-rays

A

sources : x-ray machine, starts (sun)
detectors : photographic film
uses : - produce images of bones inside the body
- CAT scans

36
Q

What are sources, detectors and uses for gamma rays

A

sources : radioactive sources eg uranium
detectors : geiger muller tube (GM counter)
uses : -medical tracers
- destroy tumours. - radiotherapy

37
Q

what Is the definition of refraction

A

refraction is when light changes speed when entering or leaving different materials

38
Q

what is a normal line

A

an imaginary line at the point of entry to an object, at a right angle to the surface

39
Q

what is the angle of incidence

A

the angle between the normal and in going ray

40
Q

what is the angle of refraction

A

the angle between the normal and the outgoing ray

41
Q

what is refraction caused by

A

refraction is caused by the difference in optical density between the tow mediums. the effect this has on the refracted wave depend on whether it is travelling from a more dense into less dense material or less dense to more dense. if it goes into a less dense material its speed and wavelength will decrease, and a more dense material they will increase. the frequency does not change

42
Q

how will light exiting a rectangular glass block look

A

the light will emerge parallel with the incident beam though offset due to the refraction.

43
Q

what are the two shapes of lenses and what do they do

A

convex lenses, also known as converging lenses, bring parallel rays of light to a focus, which is used for correcting long sight which make the light focus more quickly. concave lenses, also known as diverging lenses, cause parallel rays of light to spread out, correcting short sight by making the eye focus less quickly.

44
Q

what is the reflection of light also responsible for

A

the colours seen when white light is split into component colours when it enters a prism. red light is refracted least by the prism and violet the most

45
Q

what is total internal reflection and when does it occur

A

if a ray of light enters a semi-circular glass block it will be refracted out the other side. the angle of refraction Is greater than the angle of incident. if the angle of incidence increase, the anglo of refraction also increase. this happens until there is an angle of refraction of 90 degrees. the critical angle is the angle of incidence which causes an angle of relation of 90 degrees. if the ray of light enters the glass block with an angle greater than the critical angle, then all the light will be reflected back into the glass. this is total internal reflection.

46
Q

at what angle does total internal reflection occur at

A

90 degrees.

47
Q

what does optical fibres make use of and how

A

total internal reflection is made use of in optical fibres. light can be transmitted along lengths of fine glass fires. the light remains inside the fire because of total internal reflection. optical fibres are used a lot in the telecommunications industry as they can carry high volumes of dat eg broadband data

48
Q

where do all types of radiation come from

A

the atom. an atom consist of proton (positively charged) and neutrons (no charge) surrounded by orbiting electrons (negatively charged.)

49
Q

what are the three types of nuclear radiation and what are they

A

alpha and beta are particles and gamma radiation which is a wave and part of the electromagnetic spectrum.
alpha radiation is helium nucleus and consists of 2 protons and 2 neutrons giving it a positive charge
beta radiation is a fast moving electron which is ejected from the nucleus of an atom when a neutron splits into a proton and electron. it has a negating charge
gamma radiation has no charge as it is part of the electromagnetic spectrum. it has a very short wavelength (high frequency) and very high energy

50
Q

state the properties fo the three types of ionising radiation

A

alpha, ⍺, is 2 protons, 2 neutrons (a helium nucleus), stopped by a thin sheet of paper or a few cm of air, strength of ionisation is strong
beta, β, is a fast moving electron, stopped by 3mm aluminium, strength of ionisation is weak
gamma, 𝛾, is an electromagnetic wave, stopped by 3cm lead, strength of ionisation is weak.

51
Q

what is ionisation

A

ionisation is when an atom loses (or gains) an electron and becomes charged ionising radiation can destroy living cells, or affect their development ( sometimes resulting in cancer). this is useful in medicine as it can be used to destroy cancerous cells in tumours. it can also be used to sterilise medical equipment. the more a radiation is able to ionise the more likely it is to cause damage to, or mutate living cels. alpha is the most dangerous in this respect but it is also the least able to enter the body unless swallowed or breathed in.

52
Q

what is background radiation

A

background radiation is radiation which is present all the time. it can come from either ma-made sources or form naturally occurring sources. man-made sources include building materials, radioactive material used in medicine and radioactive materials used n smoke detectors or luminous watches. smoke alarms contain a radioactive source which his used in the detection of the smoke. natural sources of radiation include cosmic radiation form outer space, rock and mineral such as granite, radon gas from underground and even the food we eat.

53
Q

what are safety precaution that should be taken when handing radioactive substances.

A
  1. always use tongs / forceps to ice a radioactive source.
  2. always point the source away form the body.
  3. wear suitable lead line gloves
  4. never eat or drink where radioactive sources are being handled.
  5. always wash your hands after handling radioactive sources.

when storing radioactive sources

  1. keep in a lead lined container.
  2. clearly label the container with the radioactive hazard symbol
54
Q

what is the activity of a radioactive substance

A

a radioactive substance contains many nuclei which undergo decay in a random manner. the activity of a source is the number of decays per second.

55
Q

what does A, N, t mean and what are they measured in

A

A is the activity in becquerels (Bq), N is the number of nuclei decaying and t is time in seconds (s)

56
Q

what is an absorbed dose

A

when alpha, beta or gamma radiation is absorbed by the human body its energy is deposited in the absorbing tissue. this is measured by the absorbed dose which is the energy absorbed per unit mass of the absorbing material.

57
Q

what does D, E, m mean and what are they measured in

A

D is the absorbed dose ing rays (Gy), E is the energy in joules (J) and m is the mass in kilograms (kg)

58
Q

what is the equivalent dose

A

human tissue can be harmed by radiation. the amount of damage done will depend upon the size of the absorbed does and the type of radiation being absorbed, whether it is alpha, beta, gamma, neutrons or X-rays.

59
Q

what is the equivalent dose measured in

A

sieverts. the sievert is a unit which applies a weighting factor, WR, to the absorbed dose so that the type of radiation can be taken into account.

60
Q

what does H, D and WR mean and what are they measured in

A

H is equivalent dose in sievert (Sv), D is absorbed dose in grays (Gy) and WR, which is the weighting factor.

61
Q

what is the equivalent dose rate

A

people who work with radiation over long periods of time must have their exposure to radiation carefully controlled. the equivalent dose rate, Ḣ (H dot) is used to indicate the rate at which radiation is being absorbed.

62
Q

what does Ḣ, H and t mean and what are they measured in

A

Ḣ is equivalent dose rate in sievert per hour, yer (Sv h-1, Sv yr-1), H is equivalent dose in sieverts (Sv) and t is time in seconds, hours or years.

63
Q

what are medical uses of nuclear radiation

A

radiotherapy - used to treat tumours by destroying the cancer cells present in the tumour. a beam of gamma radiation is fired into the patient from several angles. the tumour being treated is targeted by every beam and receives a full dose of radiation. Surrounding healthy tissue receives a much weaker dose.
tracers - radioactive liquid can be injected into a patient and its path around the body traced using special instrument.
sterilisation - can sterilise medical instrument by destroying any organisms on them.

64
Q

what are industrial uses for gamma radiation

A

used in smoke detectors
can be used in control processes in manufacturing eg to measure the tack of a material by the amount of radiation absorbed.
tracing leaks and cracks in pipest

65
Q

what is half-life

A

over time, the activity of a source will decrease. the rate at which a radioactive source loses its radioactivity is measured by its half-life. half-life is the time it takes for the activity of a source to half. a radioactive source with a long half-life will remain radioactive for much longer than one with a short half-life. the half-life of a source can range from fractions of a second to thousands of years. the half of a source can be found experimentally by measuring its activity over a period of time using a geiger.

66
Q

how do nuclear reactors create nuclear power

A

nuclear reactors use uranium as a source of energy.the uranium is stored in fuel rods inside the reactor and a process called nuclear fission takes place where nuclei split and release heat energy.

nuclear reactor produces heat -> boiler produces steam -> steam turns turbine -> generator produces electricity.

the heat energy released from the nuclear reactions is used to turn water into high pressure steam. the steam drives a turbine which then rotates the generator to produce electricity.

66
Q

how do nuclear reactors create nuclear power

A

nuclear reactors use uranium as a source of energy.the uranium is stored in fuel rods inside the reactor and a process called nuclear fission takes place where nuclei split and release heat energy.

nuclear reactor produces heat -> boiler produces steam -> steam turns turbine -> generator produces electricity.

the heat energy released from the nuclear reactions is used to turn water into high pressure steam. the steam drives a turbine which then rotates the generator to produce electricity.

67
Q

what are the two types of nuclear reactions

A

nuclear fission or nuclear fusion. nuclear fission takes place when a neutron collide with a large unstable nucleus. this causes it to split into tow smaller nuclei. at the same time it releases more neutrons and a quantity of heat energy. in a nuclear reactor the neutrons o on to produce further fission reactions through the number of these is controlled to limit the amount of heat produced. this is called a chain reaction.
nuclear fusion takes place when two small nuclei collide and joint together to create a larger nucleus. this also causes heat energy to be released. this is the same atomic reaction that takes place in the sun. fusion requites extreme heat. at this temperature, the atoms exist as plasma (where the electrons no longer orbit the nucleus). magnetic fields must be used to contain the ;plasma as it cannot touch the container wall, otherwise it would cause the container to melt.

68
Q

what are the advantages and disadvantages of nuclear power

A

advantages :
1. a small amount of radioactive material can produce a lot of energy
2. nuclear reacts fo not produce carbon dioxide, sulphur dioxide or other pollutants.
3. nuclear reactors can supply large amounts of energy, replacing power stations powered by fossil fuels.
4. the full for nuclear reactors will last for some time
disadvantages :
1. waste from nuclear reactors must be stored underground for a long time until the radiation emitted decreases.
3. nuclear reactors are expensive to build and the time from deciding to build one and it being operational can be many years.
4. leaks of radioactive materials can have a major impact on the surrounding environment.

69
Q

what are the advantages and disadvantages of fusion reactors

A

advantages :
1. fusion fuels are widely available and nearly inexhaustible. deuterium can be distilled from all forms of water.
2. no CO2 : Fusion doesn’t emit harmful toxins like carbon dioxide or other greenhouse gases into the atmosphere. its major by product is helium: an inert, non-toxic gas.
3. No risk of meltdown : a Fukushima-type nuclear accident is not possible in tokamak fusion device. it is difficult enough to reach and maintain the precise condition necessary for fusion-if any disturbance occurs, the plasma cools within seconds and the reaction stops. the quantity of fuels present in the vessel at any one time is enough for a few seconds only ant her is no risk of a chain reaction.
disadvantages :
1. expensive to construct
2. expensive to research and develop (billions being spent)
3. extremely high temperatures (100 million degrees Celsius)
4. difficult to contain the plasma (magnetic fields/filed coils)
5. if plasma touches sides the reactor will melt.

National 4/5, Waves and radiation, physics (1 decks)

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