3.2.1 - Particles Exam ALREADY PASSED
Specific Charge-/=The ratio of the charge of a particle to its mass measured in C/kg.
\
Specific Charge = Charge / Mass
What is the Strong Nuclear Force?-/=The strong nuclear force holds protons and neutrons
together to overcome electrostatic forces of repulsion between protons to keep the nucleus
together (stable).
Strong Nuclear Force - range-/=0 - 0.5 fm = repulsive
0\.5 - 3 fm = attractive
>3 fm = no effect
What is a femtometer?-/=1 fm = 1 x 10^-15 m
Alpha decay-/=When the nucleus of an atom emits an alpha particle (2 protons and 2 neutrons)
Beta (minus) decay-/=When a neutron in the atom converts into a proton - during which a beta
particle (an electron) and an electron anti-neutrino are emitted from the nucleus.
Why were neutrinos theorised?-/=The conservation of energy in Beta decay.
\
Beta particles emitted had a range of energies up to a maximum so another particle had to be
emitted also to conserve the amount of energy lost by the nucleus.
What is an antiparticle?-/=For every particle, there is an antiparticle with equal mass and rest
energy but all other properties are opposite - e.g charge.
Antiparticle examples-/=electron - positron
proton - antiproton
neutron - antineutron
neutrino - antineutrino
What is a Photon?-/=A small packet of EM radiation. The energy of a photon is given by the
eqn:
\
E = hf
\
h - planck’s constant
, f - frequency
What is annihilation?-/=When a particle and its corresponding antiparticle meet they annihilate
and all their mass gets converted into energy in the form of two photons (to account for the
conservation of momentum).
Annihilation Equation-/=2hf = 2E
\
the combined energy of the photons = the rest energy of the particle - antiparticle pair.
\
therefore -
\
hf = E
Pair Production-/=If a photon with sufficient energy passes near an electron or nucleus then it
can be converted into a particle - antiparticle pair; these then move away from each other.
Pair Production - Equation-/=hf = 2E
\
one photon produces a particle and antiparticle.
The Four Fundamental Forces-/=Gravity
Electromagnetic
Strong Nuclear Force
Weak Nuclear Force
Gravitational Force-/=Gravity affects any particle with mass over an infinite range.
\
Its exchange particle is the graviton.
Electromagnetic Force-/=The EM force affects any charged particle over an infinite range.
\
Its exchange particle is the (virtual) photon.
Strong Nuclear Force/ Interaction-/=The SNF affects hadrons only over a range of 0 - 3fm.
\
Its exchange particle is the gluon.
Specific Charge-/=The ratio of the charge of a particle to its mass measured in C/kg.
\
Specific Charge = Charge / Mass
What is the Strong Nuclear Force?-/=The strong nuclear force holds protons and neutrons
together to overcome electrostatic forces of repulsion between protons to keep the nucleus
together (stable).
Strong Nuclear Force - range-/=0 - 0.5 fm = repulsive
0\.5 - 3 fm = attractive
>3 fm = no effect
What is a femtometer?-/=1 fm = 1 x 10^-15 m
Alpha decay-/=When the nucleus of an atom emits an alpha particle (2 protons and 2 neutrons)
Beta (minus) decay-/=When a neutron in the atom converts into a proton - during which a beta
particle (an electron) and an electron anti-neutrino are emitted from the nucleus.
Why were neutrinos theorised?-/=The conservation of energy in Beta decay.
\
Beta particles emitted had a range of energies up to a maximum so another particle had to be
emitted also to conserve the amount of energy lost by the nucleus.
What is an antiparticle?-/=For every particle, there is an antiparticle with equal mass and rest
energy but all other properties are opposite - e.g charge.
Antiparticle examples-/=electron - positron
proton - antiproton
neutron - antineutron
neutrino - antineutrino
What is a Photon?-/=A small packet of EM radiation. The energy of a photon is given by the
eqn:
\
E = hf
\
h - planck’s constant
, f - frequency
What is annihilation?-/=When a particle and its corresponding antiparticle meet they annihilate
and all their mass gets converted into energy in the form of two photons (to account for the
conservation of momentum).
Annihilation Equation-/=2hf = 2E
\
the combined energy of the photons = the rest energy of the particle - antiparticle pair.
\
therefore -
\
hf = E
Pair Production-/=If a photon with sufficient energy passes near an electron or nucleus then it
can be converted into a particle - antiparticle pair; these then move away from each other.
Pair Production - Equation-/=hf = 2E
\
one photon produces a particle and antiparticle.
The Four Fundamental Forces-/=Gravity
Electromagnetic
Strong Nuclear Force
Weak Nuclear Force
Gravitational Force-/=Gravity affects any particle with mass over an infinite range.
\
Its exchange particle is the graviton.
Electromagnetic Force-/=The EM force affects any charged particle over an infinite range.
\
Its exchange particle is the (virtual) photon.
Strong Nuclear Force/ Interaction-/=The SNF affects hadrons only over a range of 0 - 3fm.
\
Its exchange particle is the gluon.
