Particles Flashcards
Overall the atom is ____
neutral
What is an isotope
An isotope of an element has the same number of protons but a different number of neutrons
are all isotopes stable
No, carbon 12 is stable while carbon 14 is unstable
What are the 3 types of nuclear radiation
Alpha, beta, gamma
When does nuclear radiation occur
An unstable nuclei can emmit radiation to become stable again.
Describe Alpha radiation
Alpha radiation takes the form of a helium nuclei with an atomic number of 2 and atomic mass of 4 (2 protons and 2 neutrons) This means it has a +2 charge. They are given the symbol He. α.
Describe Beta radiation
Beta radiation takes the form of fast moving electrons. These have an atomic number of -1 and atomic mass of 0 and are given the chemical symbol e. They have a charge of -1. β.
Describe gamma radiation
Gamma radiation takes the form of a high frequency EM wave. It has a charge of 0. γ
When nuclei decay what happens to the mass and atomic number
They are conserved. THis means the to value is the same before and after the decay.
When gamma is emmitted what happens to the decay equation
Only energy is emmited and the daughter product is the same as the parent.
Define nuclear fission
Nuclear fission is the splitting of a heavy nucleus into 2 nuclei of smaller mass number, with the release of neutrons and energy.
What 2 ways can nuclear fission occur in
Spontaneously or by bombardment of neutrons (induced fission)
What does Einsteins equation show
mass is equivalent to energy
State Einsteins equation
E=mc^2
E = energy in Joules(J)
m = mass in kg
c = speed of light
Why is energy released in a fission reaction
The mass after a fission reaction is slightly less than the mass before (although the total mass number doesn’t change)
This “lost mass” is converted to energy (according to e = mc^2), and released as kinetic energy of the fission products.
Define nuclear fusion
Nuclear fusion is when two light nuclei combine to form a larger nucleus
Is mass conserved in fusion
No in nuclear fusion mass is “lost” in the process which is converted to energy and released as kinetic energy of the fusion products
What temperature is required to fuse two nuclei together
about 100,000,000 K
How do stars achieves fusion
Stars achieve nuclear fusion with a core at only 15,000,000 K because the heat energy is combined with enormous pressure. This process lead to four million tonnes of mass being lost every second and released as energy.
How do we measure order of magnitude
Difference in order of magnitude = difference in power
What is the standard model
The standard model is a model of fundamental particles and their interactions.
What is a fundamental particle
A fundamental particle is a particle that cannot be divided into smaller particles.
What are the two types of fundamental particles
Matter particles and Force mediating particles
What are fermions
Fermions are the matter particles that include all quarks and leptons.
What are protons and neutrons made up of
Different types of fermions called quarks
How many types of quark exist
6
Why are quarks never seen on their own
Each quark has a fraction of the charge of an electron.
What are the 6 quarks
Up (+2/3e) Charm (+2/3e) Top (+2/3e)
Down (-1/3e) Strange (-1/3e) Bottom (-1/3e)
What is the evidence for the existence of quarks
high energy collisions between electrons and nucleons inside particle accelerators
What is ordinary matter (Protons and neutrons) made up of
Up and down quarks.
Strange, charm, top and bottom quarks only appear in
exotic matter
What are hadrons
Hadrons are particles made from quarks. held together by the strong force.
What are the two types of hadron
Baryons and Mesons
What is a baryon
A hadron made up of 3 quarks or 3 anti quarks (ie protons and neutrons)
What is a meson
A hadron made up of 1 quark and 1 anti quark
What quarks make up a proton
2 up quarks and one down quark giving a charge of 1e (+1.6x10^-19c)
What quarks make up a neutron
1 up quark and 2 down quarks giving a charge of 0e or 0C
Each elementary particle (matter) has…
its own antiparticle (antimatter)
How are antiparticles different from elementary particles
they are the same in all respects but have an opposite charge of equal size (ie positron is the anti particle to the electron)
What happens when a matter particle meets its anti matter particle
they are likely to annihilate each other producing gamma rays. The energy released is evidence of the existence of anti matter.
What are leptons
Leptons are matter particles (fermions) with virtually no size or mass.
How many leptons are there
3 generations (6 in total)
Which leptons occur in ordinary matter
Electrons
Name the 6 leptons
Electron neutrino (Ve)
Electron(e)
Muon neutrino (Vm)
Muon (M)
Tau neutrino (Vt)
Tau(T)
What are the 4 fundamental forces
Gravitational force
Electromagnetic force
Weak (nuclear) force
Strong (nuclear) force
What does gravitational force act on
mass
What is the relative strength of gravitational force
weakest of the fundamental forces
What is the range of the gravitational force
Infinite
What is electromagnetic force
Combination of the electrostatic and magnetic fields
What does electromagnetic force act on
charged particles
What is the relative strength of electromagnetic force
Stronger than gravitational forces
What is the range of the electromagnetic force
Infinite
What is the weak nuclear force associated with
Beta decay
What can the weak force change
The flavour of a quark. ie a down quark into an up quark
What is weak force experienced by
Leptons and quark interactions
What is the relative strength of the weak force
Weaker than strong force
What is the range of the weak force
Short
Beta decay was the first evidence for…
the existence of neutrino
Electrostatic theory suggests that…
Protons in the nucleus should fly apart.
What role does strong force play
holds protons together (ie in the nucleus)
What is the strong force experienced by
quarks
What is the relative strength of the strong force
Stronger than electromagnetic force (strongest of the 4)
What is the range of the strong force
Very short range
What are bosons
force carriers
How many bosons are there
4
Name the 4 bosons and the force they carry
Photon - electromagnetic
Gluon - Strong
W boson - weak
Z boson - weak
What is the 5th (theoretical) boson and what force does it carry
Graviton - gravitational
What is the higgs boson
The higgs boson is responsible for giving particles mass.
What is the grand unified theory
A theory linking together all the force into one. At high energies the strong, weak and electromagnetic forces are all merged into one electronuclear force. Unifying gravity with this would provide a comprehensive theory of everything.
An electric field produces…
force on a charged particle
The electric field pattern around a point charge is…
radial, like the radii of a circle. They never cross and are always drawn from positive to negative. Showing the direction that a positive test charge would move in the field.
What do closer field lines indicate
stronger electric field
What do parallel evenly spaced field lines indicate
a uniform electric field.
the tangent to a field line at a point gives…
the direction the field at that point
In an electric field work is done to…
move charges
State the work done formula
Ew = QV
Ew = Work done (Joules (J))
V = Voltage (Volts (V))
Q = Charge (Coloumbs (C))
Define potential difference (Voltage)
The voltage between two points is the work done in moving unit positive charge (1 coulomb) between two points
A potential difference of 3 volts would mean…
3 Joules of work is to move one coulomb of charge
Describe an electron gun in terms of work done
In an electron gun, electrons are accelerated from the cathode (-) to the anode (+). Work has to be done by the field to move the electrons and the electrons gain kinetic energy (conservation of energy)
What do magnetic fields exist around
Permanent feromagnetic material
Moving charges
What is the left hand grip
The direction of the magnetic field around a wire is found using the left hand grip rule where the thumb points in the direction of the current while the curved finger gripping the wire indicate the direction of the magnetic field.
Charges moving in a magnetic field will experience a…
force
What is the right hand rules used for
The right hand rule can predict the direction of the forces on a current carrying wire (ie moving negative charges in a magnetic field)
The size of the force experienced by a moving charge in a magnetic field depends on what 4 things
The speed of the charged particle
The size of the magnetic field
The charge of the particle
The direction of motion of the charged particle
When do moving charges produce a circular path of movement
If the charged particle is moving with a constant velocity perpendicular to the magnetic field
What do particle accelerators do
A particle accelerator is designed to accelerate particles usually to cause high energy collisions between charged particles in order to produce other particles.
How are particle accelerators used in medicine
Particle accelerators are used to produce x rays and ions for medical physics treatments of cancer.
What are the two types of particle accelerator
Linear accelerators (LINACS)
Circular accelerators (Cyclotron and Synchrotrons)
How do linear particles accelerators work
Particles are accelerated by electric fields via a linear series of charged conductors. They are accelerated by an electric field that is applied across the gap between drift tubes. The particles travel at a constant velocity within the drift tubes, sa they leave these tubes they are repelled from the one they left and attracted to the next which is achieved by alternating the polarity of the tubes.
How does a cyclotron compare to a LINAC
they are more compact and can accelerate particles to greater energies.
How are charged particles accelerated in cyclotrons
By alternating electric fields and deflected by magnetic fields so that they follow a spiral path.
How does a synchrotron compare to a cyclotron
A synchrtron has a single ring. like the cyclotron magnetic field are used to steer (Deflect) the particles around the curved path. However, this time their strength can be varied to keep the particles in a single path rather than a spiral.
This allows them to be accelerated around the ring many time to reach extremely high energies.
Using two synchrotrons in succession to collide particles are energies…
equivalent to just after the big bang.
