Quanta to Quarks Flashcards
1
Q
what experiment helped to provide evidence for rutherfords model of the atom?
A
the gold foil experiment( or rutherfords scattering experiment)
2
Q
who performed the gold foil experiment?
A
hans ginger ands Ernest Marsden under the direction of Rutherford
3
Q
what did the gold foil experiment involve and what were the results?
A
-alpha particles were emitted from a source, through a collimator at a piece of thin gold foil, with a detector situated on the other side of the foil
most of the particles passed through the foil with little to no deflection, but 1 in 8000 alpha particles were deflected back at an angle greater than 90 degrees, which had been identified via the detector
4
Q
what did Rutherford propose as a result of the gold foil experiment?
A
he proposed that the only way that the alpha particles could be deflected through large angles was if all the atoms positive charge and nearly all of its mass was concentrated in a small dense nuclear with the electrons a very large distance away.
the fact that most of the alpha particles went through the foil led Rutherford to believe that the atom was mostly to a high degree empty space
5
Q
by using the results of the gold foil experiment, Rutherford found that the size of the atom was…
A
10^-10m in diameter
6
Q
Rutherford found that the size of the nucleus was…
A
10^-14m in diameter
7
Q
compared with the size of the atom, the nucleus is…
A
10000x smaller
like a grain of sand in my bedroom
8
Q
what were the problems with rutherfords model of the atom?
A
- if the electrons circled the nucleus of the atom like planets orbiting the sun, they would be accelerating. but accelerating charges are known to hit electromagnetic radiation, and so the electrons would be constantly losing energy and spiral into the nuclear and the atom should collapse upon itself. but this isnt the case obviously
- rutherfords model could not exactly describe what the nucleus was made of, how the electrons were arranged and could not explain why the electrons were not attracted to the positive nucleus
9
Q
what was the good thing about rutherfords model of the atom?
A
the model was essentially a simplified version of the model that is used today.
it was ground breaking at the time as it was a step in the right direction for other scientists to build upon
10
Q
what was bohrs first postulate and what did it account for?
A
1) electrons can revolve/exist in stationary states of stability and emit no energy when in these states. they can revolve in certain allowed orbits
this idea accounted for the observed stability of atoms. why these stationery states existed was unknown, but it was a fact that they did exist
11
Q
what was bohrs second postulate and what did it account for?
A
2) energy is lost or gained by an electron as it moves from state to state, and when it moves from a higher energy state to a lower energy state, it releases a photon with energy equal to a difference between the states( and therefore a characteristic frequency)
this photon energy is quantised by the Planck relationship/equation
this postulate accounted for the line emission spectra of atoms
- emission(or absorption) of energy is discontinuous and corresponds to a transition between two stationary states
- a transition between different states will lead to different frequencies or colours
12
Q
what was bohrs third and final postulate and what did it mean?
A
3) electron angular momentum in a stationery state is equal to an integer value of h/2(pie)
this postulate sets limits on the radius of the allowed orbits
13
Q
what were the two general limitations of the Bohr model of the atom?
A
- still did not explain why there is no energy emission by the accelerating electrons as predicted by Maxwell, instead it was simply assumed that this didn’t happen
- there was no evidence for the existence of the Bohr model to grant it scientific credibility
14
Q
what were the four areas of the emission of spectra that the Bohr model couldn’t explain and describe them
A
-the spectra of large atoms with more than one electron
only one electron ions or atoms applied to bohrs model. this is because for larger atoms outer electrons are shielded from the nucleus by the inner electrons. interactions between electrons also result in different energy levels
-the relative intensity of spectral lines
when the spectrum for hydrogen was closely examined it was noted the emission lines varied in intensity , some were quite intense and others were less intense, some were sharp, others were diffuse
-the existence of hyperfine lines
as spectroscopes got better, spectra could be more closely examined, and it was found that each line actually consisted of many other small lines
-the Zeeman effect
in 1896 a dutch physicist Pieter Zeeman found that when he placed a source of sodium emission light between the poles of a strong magnet the lines split into three
some even split into 15 in other atoms
15
Q
what was de broglies big idea?
A
suggested that any fundamental particle had wave-particle duality
16
Q
via de broglies idea of wave-particle duality, what can exist?
A
matter waves and things like tennis balls or elephants can have whats called a de Broglie wavelength
17
Q
what were the impacts of de-broglies ideas?
A
-provided a model to accompany bohrs first postulate that there were stable orbits where electrons did not emit any energy
this gave the Bohr model the credibility it required to be accepted and developed upon by the scientific community, which provided vital in understanding the structure of the atom
-de broglies principles has also been used to make electron microscopes, exploiting the wave particle duality of them.
these are used to image objects at far greater resolution than was possible with light due to the smaller wavelength of electrons
-de broglies proposal also reconciled Einsteins theory of light with classical physics by showing that light could have both wave and particle nature
18
Q
define diffraction
A
the bending of light around obstructions. purely a wave property
19
Q
what does the amount of diffraction depend upon?
A
it depends on the size of the obstruction, and is greatest when the obstruction is of the same order as the size of the diffracting waves wavelength
20
Q
why does interference occur when a wave is diffracted?
A
when a wave diffracts around an obstruction,
the corners of that object act as point sources for the wave, resulting in a curved wave that radiates outward
there now exist two waves, the point source waves and the original that can super impose one another
21
Q
if the two waves during diffraction arrive at a particular point in phase, such that a crest meets a crest and a trough meets a trough,….
A
they reinforce each other and constructively interfere
22
Q
if the two waves during diffraction arrive at a particular point where a crest meets a trough,…..
A
they effectively cancel each other out and therefore destructively interfere
23
Q
via diffraction, interference creates…
A
a combination of bright(constructive) and dark (destructive) fringes. if the obstruction is circular, light and dark rings form
24
Q
from de broglies hypothesis, what it possible to be derived?
A
bohrs third postulate
25
how did heisenberg contribute to the development of atomic theory?
-devised matrix mechanics to explain the atom in terms of quantum probabilities, rather than mixing classical quantum theory which bohr had down
this lead to an entirely quantum theory of the atom, helping to mathematically understand its nature
-he devised the heisenberg uncertainty principle, effectively says that for every elementary particle, the more pricely the position is dtermined, the less precisely the momentum is known in the instant and vice versa
this changed the way science viewd atomic structure, by this theory electron orbits postulated by bohr could not exist, it led to the idea of electron clouds rather than orbits where an electrons position could not be determined due to a statistic probability
this uncertainty principle is the most central principles of quantum mechanics, tha knowledge of one thing can be mutaully exclusive to knowledge of another
made physicists rethink the way they designed their experiments and caused them to have more realistice expectations regarding the precision they could hope to achieve with their measurement
26
what ideas did pauli propose which contributed to the worlds understanding og atomic theory?
- took the quantum mechanical medoel which was entirely theoretical and applied it to the hydrogen atom to derive rydberg constant and to devleop Balmers equation
- pauli used bohrs idea of electron shells and developed the exlusion principle in which he introduced a new quantum number known as spin to explain the max no. of electrons in energy levels. no two electrons can have the same set of 4 quantum numbers
- pauli proposed the existence of the neutrino, another significant subatomic particle
27
how did paulis idea of the exclusion principle impact on quantum theory?
- paulis exclusion principle accounted for the max no. of electrons in each shel around a nucleus, and derived it to be 2n^2 where n is the shell number
- his principle was later discovered to aply to all fermions(a class of sub particles in which the electron is one)
- provided a quantum explanation for the position of the first 20 elements in the periodic table
- explained why the heavier atoms are so much larger than the lighter ones---> the extra electrons have to find space in new orbitals further and further out. also explains why even at low temp, most conduction electrons in a matallic crystal are still in high energy states, and very mobile
- able to exaplin the zeeman effect
28
what do you classify protons and neutrons as?
nucleons
29
constrast the proton and the neutron
- both have a mass of the same order, but the neutron is slightly heavier
- the proton has the same magnitude of charge as an electron, but opposite in sign
- the neutron has no charge. this means protons are affected by magnetic fields and electric fields while neutrons arent
30
whats the mass of a proton and a neutron?
1.673 and 1.675 respectively to the order 10^-27Kg
31
in 1930, what did german physicist and mathematician walther bothe and his student herbet becker discover?
discovered that bombarding berylium with alpha particles resulted in the emission of a penetrating type of radiation. this radiation proved not to be gamma rays even though these were expected penetrating radiation as they could not be detected using a cloud chamber and didnt appear to be a particle
32
what did english physist james chadwick suggest was the nature of this penetrating radiation?
he suggested that this radiation was rutherfords neutron
33
how did chadwick detect the neutrons?
he placed a parrafin wax, rich with hydrogen, in front of the berylium. because uncharged neutrons were hard to detect, as they caused little to no ionisation, the addiation of this wax would be used to ehance the detection through a detector
-the neutrons ejected from the berylium would eject protons from the wax as a result of elastic collisions, and as the collisions cause ionisation they're readily detected
34
what laws did chadwick use to prove the existence of the neutron?
law of conservation of energy and law of conservation of mass and number
35
how did chadwick use the law of conservation of energy to prove the existence of the neutron?
well, the energy of the released protons had been measured to be 5 milli electron vol, implying that if the unknown radiation was gamma radiation, it would have had an energy of 50 milli electron volts
this was problematic because the original alpha particles had only energy of 5 milli electron volts
this implied that there was a tenfold increase from the alphar particles in creating the unkown radiation, and hence this violated the law of conservation of energy
but, chadwick realised that a neutral particle such as a proton would be capable of colliding with a proton and imparting the observed momentum without violating conservation laws.
thus the law of conservation of momentum was vitally important for chadwic and his discovery of the neutron
36
how did chadwick use the law of conservation of mass and number to prove the existence of the neutron?
by adding the mass numbers, according to conservation of atomic mass laws, there would have been present an unkown particle with the same mass as a neutron to explain the result of the investigation
thus through conservation of mass chadwick was able to prove the existence of the neutron (and show that initially observed radiation was infact a particle)
37
why do we need a strong nuclear force to exist?
because, in an atom, the electrostatic repulsion between protons is far to high compared to the gravitational attraction that pulls them close together. if the force didnt exist, all atoms would explode
infact, the gravitational force is so small that it is diregarded during calculations
38
what are the features of the strong nuclear force?
- the force neglects charge and is equal and similar between proton-proton, proton-neutron and neutron-neutron
- only acts between neighbouring nucleons, not the entire nucleus
- the strong nuclear force is known as the strongest known force in the universe
- the strong nuclear force is only
experienced over a very small range
at extremely short distances it is
repulsive, then it becomes attractive as distance increases, then increasingly weaker at larger distances
at distances over 2x10^15m, the force is effectively zero. if the distance between nucleons becomes less than 0.5 x 10^15m, the force is repulsive
there exists a balance of seperation where at a particular point, the two forces are balanced and the nucleus is stable
39
describe the trail of alpha particles in a cloud chamber and relate them to their properties
- forms strong trails because they are more highly charged, and therefore ionise mroe air as they travel( resulting in more condensation).
- their trails are also shorter than beta particles, becuase their strong charge causes them to attract electrons rapidly, so before they travel a long distance they get converted to neutral helium, and therefore can no longer ionise the air--> same reason that alphar radiation is both not very penetrative, yet highly dangerous inside the body
alpha trails are relatively straight, because the large mass of the alpha particle means that it will be deflected less by other particles as it travels
40
describe the trail of beta particles in a cloud chamber and relate them to their properties
- form less intense trails because their ionisation strength is not great
- react less with their surroundings, and hence travel a longer distance
-beta particles have a very low mass, and so are very susceptible to having their path changed through interactions/collisions with other particles.
however, their path is still quiete straight because of their heigh velocity and low charge which means that they are less liekly to have their path changed
41
what are the parts to a wilson cloud chamber?
-radiation source
-glass container filled with a supersaturated water or alcohol vapour.
the vapour can be made DIY by placing filter paper sealed in methylated spirits inside the container
42
how does a wilson cloud chamber work?
as radiation passes through the chamber, the air or vapou is ionised with the ions serving as nucleation points in which vapour may form droplets. the droplets form clouds or trails showing the path of the radiation
gamma radiation trails are very fine lines and often cannot be observed
43
which physicist proposed the existence of the neutrino?
wolfgang pauli
44
what was the exisence of the neutrino used to account for?
the variable beta particle velocites and to fufill conservation of momentum
during beta decay, initially scientists thourght only beta particles were emitted. when they evaluated the energies involved, they came up with a figure for the max kinetic energy that a beta particle should have, all beta particles should have been emitted with this velocity, but this wasnt the case.
most of them were emitted with significantly less. this meant that the slow beta particles were missing kinetic energy, leading to a violation of conservation of energy
also the sum of the momentums before and after the beta decay were not equal. assuming the nucleus starts off stationary, the sum of the momentums should be zero. however when the momentums of the beta particle and the remainder of the nucleus were added, it was not zero, so conservation of momentum was being violated
45
what were the impacts of pails neutrino?
-without pails postulated particle, the well established laws of conservation of energy, mass and angular momentum would have to be abandoned; an idea that did not sit well with Pauli
fermi used the concept of pauli's neutrino to come up with a theory of beta decay that corresponded with experimental data
46
what were the issues with the neutrino?
-could not be detected at the time. therefore it critically lacked evidence because scientists at the time could not detect neutrinos. it was until 20 years later using more advanced technologies that the particle was detected
later they were shown to be antineutrinos
47
define transmutation
nuclear reaction where an element is transformed into another because the number of protons in the nucleus has changed as a result of either alpha or beta decay
48
what are the two types of natural radioactive decay which cause transmutations?
alpha and beta decay
49
what is an alpha particle?
a helium nucleus with 2 protons and 2 neutrons
50
what happens during alpha decay?
the nucleus of a radioactive element emits an alpha particle consisting of two protons and two neutrons, in the process reducing its mass by 4 and its atomic number by 2
51
often in alpha decay the equation is a little bit off from what actually occurs (alpha particle is charged but often its charge is ommitted). why is that?
the alpha particle rapidly gains electrps from surrounding atoms and hence loses it charge very quickly. hence its charge is ommitted often when writing equations
52
what is a beta particle?
an electron with a mass number of 0 and an atomic number of -1
53
what are the two types of beta decay?
beta-minus and beta-plus decay
54
what happens during beta-minus decay?
a neutron is converted into a proton, emitting a beta particle and an antineutrino, which is an antiparticle of the neutrino. the proton remains in the nucleus
55
what happens during beta-plus decay?
essentially the opposite of beta-minus decay. a prton is converted into a neutron, emitting a positron and a neutrino. the neutron remains in the nucleus
56
what is gamma radiation?
a high energy photon
57
why does gamma decay occur and does it lead to transmutations?
gamma radiation is released when the protons and neutrons in the nucleus of an atom rearrange into a lower energy arrangment. as this does not change the atomic number of a nucleus, it does not lead to transmutations
58
whats a word equation for the process of beta-minus decay?
neutron --> proton + electron + antineutrino
59
whats a word equation for the process of beta-plus decay?
proton --> neutron + antielectron + neutrino
60
what is mass defect/ binding energy and how are they related in terms of einsteins idea?
tha actual mass of a nucleus is always less than the sum of the masses of the constituents of its nucleus
e.g a helium nucleus with 2 protons and 2 neutrons has less mass than the combined mass of 2 neutrons and 2 prtons measured seperately-----> this is called the mass defect
the mass defect is converted into the binding energy of the nuclues---> the energy needed to seperate the nuclues into its seperate parts.
the two are related via einsteins idea of mass-energy equivalence in E=mc^2
61
what are the two formulas for finding binding energy and when are they used?
E=mc^2 is used when the mass defect or energy is given in SI units
E= 931.5 x m is used when the energy is given as a factor MeV or when the mass is given in factors of amu
62
so in general terms, what happens when nucleons of an atom form a nucleus?
they form a nucleus but release energy in the process called the binding energy
63
in general, how can i represent binding energy formation?
n protons + n neutrons -----> a nucleus + binding energy
64
which italian physicist was the first to observe artificial nuclear fission?
Enrico Fermi
65
what was fermi and a bunch of other scientists doing which led to the observation of nuclear fission?
they had been bombarding heavy nuclei with neutrons to observe their properties.
66
why was fermi using neutrons in his bombardment of heavy nuclei to study their properties?
Unlike the alpha or beta particle, the neutron experiences no electrostatic repulsion or attraction with other subatomic particles. Because there is no electrostatic barrier, even very slow neutrons can penetrate and interact with even the most massive, strongly positively charged nucleus.
67
what had fermi hoped for when he bombarded uranium 235 with neutrons and was he successful?
he was hoping that the uranium would capture the neutron and immediately undergo beta decay to produce transuranic elements heavier than uranium.
He was not successful and his results were very puzzling
68
why were fermi's results puzzling regarding the bombardment of uranium-235?
he found that instead of undergoing beta decay to produce heavier transuranic elements, he observed the production of separate products each with different half-lives. This was his first observation of fission, although he did not realise what was happening in his experiment.
69
who were davisson and germer?
two scientist who found evidence for de broglies proposal of matter waves
70
what apparatus were davisson and germer using in their experiments?
- a heated tungesten electrode (electron gun)
- a large potential difference
- a nickel target
- movable detector
- vacuum tube
71
what happened during davisson and germer's experiment which had played to their advantage unseemingly?
the vacuum tube had become damaged, and the nickel target had allowed to be oxidised forming nickel oxide impurity
72
what did davisson and germer decide to do in order to remove the impurity and what effect did this have on the nickel target?
they decided to heat it up in order to destroy the impurity. but this caused the nickel target to anneal, allowing it to crystallise in such a way that formed a very large crystal structure and making its surface very smooth
73
what happened when davisson/germer fired the electrons to the target?
the electrons were accelerated toward the target via a potential difference, being preferentially deflected off the target at difference angles and velocities. this was picked up by the movable detector producing an interference pattern. this result provided direct evidence to suggest that electrons were waves and particles.
74
who built the first ever self sustaining nuclear chain reaction, when and where?
december 2nd in chicago state university. fermi and a group of scientists
75
what three main parts did fermi's atomic pile consist of and why were they important?
- source of natural uranium (approximately 40tons).
- 40000 blocks of alternating graphite blocks acting as a moderator, slowing down the neutrons so they may interact more with the nucleus of the uranium. slowed down via collisions with the carbon atoms
- cadium rods, used as control rods and a mechanism to absorb neutrons so that amount of neutrons causing fission was kept constant and hence so that the reaction was controlled.
76
what is an uncontrolled nuclear reaction and what are its requirements?
a nuclear reaction were eacj fission causes more than one fission to occur , causing a rapid build up of atoms and an exponential increase and release of energy.
requirements
- super critical mass of fissionable material
- way to slow neutrons down
77
what is a controlled nuclear reaction and what are its requirements?
nuclear reaction where number of neutrons causing fission is kept constant by an absorbing mechanism which absorbs some of the neutrons
requirements:
- super critical mass of fissionable material
- way to slow down neutrons
- mechanism to absorb some of the neutrons
78
what is the critical mass of fissionable material?
the minimum amount of material required so that the neutrons emitted from fission go on
to cause further fission reactions in a chain reaction, sustaining the reaction
79
what are the six quarks and what are their electric charges?
```
up +2/3
down -1/3
charm +2/3
strange -1/3
top +2/3
bottom -1/3
```
80
what is a fundamental particle and what are some examples of such?
a fundamental particle is one that cannot be broken down into smaller known components
these include:
quarks, antiquarks
leptons, anileptons
81
what are the 3 fundamental forces and which particles mediate this forces?
strong nuclear force- gluon
weak nuclear force - W and Z boson
Electrostatic force - Photon
82
what is a hadron?
a particle made constructed from a combination of quarks and or antiquarks
examples include:
neutron
proton
83
what are the two types of hadrons and what are they made from?
baryions (three quark combination) and mesons (combination of a quark and antiquark )
84
whats a lepton and what are its properties?
- fundamental particle
- does have colour charge
- doesnt experience the strong nuclear force
- can interact through the strong nuclear force
85
what are the six types of leptons and what are their charges?
```
electron -1
muon -1
tau -1
electron-neutrino 0
muon-neutrino 0
tau-neutrino 0
```
86
what is the purpose of a nuclear reactor?
to create nuclear energy and to convert this energy into electrical energy by creating steam which turns a turbine
87
what are the basic requirements for a fission reactor?
- fuel rods
- suitable moderators
- control rods
- coolant
- appropriate shielding
88
describe the fuel rods used in a fission reactor
consits of enriched uranium in the form of uranium oxide pellets inside steel fuel rods that can be inserted or removed to control the rate of reaction
Each fuel rod contains a sub-critical mass of fissionable material. When several of these rods are arranged vertically in the reactor core at suitable close distances in a geometric array, the effect is that a critical density of fissionable material is achieved.
89
what is a moderator, why is it important and what are some common moderators used in a fission reactor?
a moderator is a compound containing atoms and particles which can collide with neutrons to lower their kinetic energies, converting this into heat
they are important because slow thermal neutrons are better able to penetrate deeply into the nuclei of atoms. when fission occurs these are released at very high energies, hence they need to be slowed down by something
common moderators include:
- water
- heavy water
- graphite, as fermi had used in his atomic pile
- beryillium
90
why is a coolant needed in a fission reactor?
To allow the heat produced by the core to be used to turn a turbine( and so that the core doesn’t melt) , the moderator liquid also acts as a heat exchange fluid that carries the heat away from the reactor to produce steam, which drives the turbine. The reactor shown above is the type which has a primary fluid loop of liquid sodium which heats a secondary loop of water, producing steam to turn the turbine.
91
why are control rods needed in a fission reactor and what are they made of?
Control rods consisting of cadmium or boron are placed in the reactor, such that they can be moved in and out to control the reaction. The control rods absorb excess neutrons to prevent the reaction from taking place too quickly.
When they are lowered, more neutrons are absorbed and the reaction slows, and when pulled out the reaction rate increases. Stops reactions from getting out of control.
92
what are some health issues regarding the operation of a fission reactor and how are they illeviated?
Spent fuel rods that have been depleted in the reactor are extracted and processed or stored. They are extremely radioactive, making them very difficult to dispose of
these are avoided through SHIELDING, those such as :
-Graphite: reflects neutrons back into the core
- Thermal: prevent unwanted heat loss from the core
- Pressure Vessel: surrounding the core to isolate and contain everything inside the core
- Biological: bout 3 metres of concrete mixed with lead pellets, to absorb gamma rays and neutrons, thus protecting those monitoring the reactor
93
what was the mannhattan project?
The Manhattan Project was a research and development undertaking led by the United States during World War II that produced the first nuclear weapons, Little Boy and Fat man which had been dropped on the Japanese cities of hiroshima and Nagasaki respectively.
Constructed with advanced knowledge that most likely that Germany was going to develop its own nuclear weapons program, aided by a group of multinational, mostly German scientists including most exclusively Albert Einstein.
94
what were some of the positive impacts the manhatten project bestowed upon society?
- provided a possible new source of electrical power through the conversion of nuclear energy, alleviating the problem of depleting fossil fuels and the increased effect of greenhouse gases on the environment
- although debatable, the bombs provided an end to the war in the Pacific, possibly even saving the lives of many whom would have died if the war had continued on
- has lead to many applications and developments in the area of nuclear physics including isotopes used in engineering, agriculture, and medicine as well as in the development of accelerators which have been used to better study the structure of matter. higher quality of life.
- can be argued that the increased fear and mutually assured worry of the total nuclear annihilation of the globe in the event of nuclear warfare has deterred many wars between superpowers in contemporary society. this has potentially saved the lives of hundreds to nearly thousands of people.
- lead to a greater understanding in the process of fission
- Through the aftermath of the nuclear fallout which had decimated approximately 100,000 Japanese civilians, in can be argued that scientists had gained an insight into the potential health problems caused by radiation poisoning and also the long term genetic ramifications which are involved.
95
what were some of the negative impacts the Manhattan project bestowed upon society?
- lead to the death of hundreds of thousands of Japanese
- May have been unnecessary in stopping the Pacific war and may be seen as a political statement highlight that the US was not afraid to use nuclear weapons
- Established a continued fear in society that nuclear warfare could end the world and their lives. Moves into the cold war which saw mass paranoia and political tension between the USA and USSR. Used as a dangerous bargaining chip by rogue states today such as North Korea
- Long term genetic side effects due to radiation poisoning, restricting affected civilians in practicing their fundamental human rights in raising a child
- Hiroshima didn’t exist for a period of 10 years.
96
what are three radisotopes used in industry today?
medicine- technitium 99m
engineering- Cobalt 60
Agriculture- Phosphorous 32
97
describe the use of technitium 99m in medicine?
- used in medical diagnosis to create images to detect bodily issues including tumours, blood flow abnormalities, heart defects and cancerous growths
- may attach to other compounds and circulate in the bloodstream, can provide images of the lungs, heart, kidneys and liver
98
what are some of the properties of technitium 99m that make it suited for its use?
- not absorbed by the body, therefore minimsing damage
- has a half life of roughly 6 hours, the radiosotope decays rapidly and hence causes minimal damage
- radition emitted is of low energy which further minimsies damage inside the body
99
describe the use of cobalt-60 in engineering?
- used to gauge metal thickness, detecting any structural faults in metallic structures by showing variations in thickness of the material. important in detecting faults in aircraft
- causes ionisation and hence darkening of photographic film to varying degrees, showing variations in thickness of the material
100
what are some of the properties of colbalt-60 that make it suited for its use?
- when it decays , it emitts penetrative beta and gamma radiation, where beta emission causes the ionisation of photographic film on the other side of the strcuture, degree of darkening shows variation in thickness
- half life of roughly 5.3 years, reduces frequency of maintanence and associated costs, the compound can be placed in a box inside the structure
- relatively low ionising emission which mimises damage enforced on workers handling the isotope
101
describe the use of phosphorous 32 in agriculture?
- similar in use to technitium, used as a tracer to detect and monitor the movement of nutrients in crops/plants. it substitues phosphorous in fertilier and allows tracking of its uptake
- by using a gieger counter, the path, use and concentration of the nutrients can be determined
- this use allows for better understanding of the conditions favourable for plant growth, thereby maximising yield and increasing efficiency and economy of the farming process
102
what are some of the properties of phosphorous 32 which make it suited to its use?
- half life of 14.3 days, minimses exposure to the environment
- beta emitter, and hence can cauase ionisation and be detected by the gieger counter
103
what are some properties of neutrons which make them suited to act as probes? relates these properties to its application as a probe
- similar mass to a proton, is not electrically charged and hence is not affected by electrostatic fields generated by protons or electrons --> can penetrate deeply into dense materials, such as AIRCRAFT ENGINES AND WELD JOINTS
- neutron has a de-broglie wavelength allowing it to interact with materials on the atomic level--> useful when studying the PROPERTIES OF SEMICONDUCTORS IN THE PRODUCTION OF INTEGRATED CIRCUITS... if the wavelegnth is comparable with the inner-atomic lattice spacing than an interfernece pattern will result which can be analysed. useful in the study of BIOLOGICAL SUBSTANCES OR INORGANIC SUBSTANCES SUCH AS PHARMECUTICALS
- has energy that is similar to the energy of atomic vibrations in solids and liquids---> useful in analusing other properties of atoms... slow thermal neutrons are used in a controlled fission reaction where a uranium nuclei splits with the release of energy
