PARTICLES AND WAVES - Standard model and fields Flashcards
Describe Bohr model of an atom
Electrons orbit the nucleus in orbits
that have a set size and energy.
The energy of the orbit is related to its size.
The lowest energy is found in the smallest orbit.
Radiation is absorbed or emitted when
an electron moves from one orbit to another.
Fundamental particles can be split into two main groups:
Fermions and bosons
Fermions are particles which have mass and can be split into two types
Baryons and Leptons
Describe Beta decay
- Neutron in nucleus of atom
- Down Quark converts to up
- Neutron is now a proton
- Weak force W boson is required for
conservation of charge - An electron (beta particle) and electron
antineutrino are produced
The Standard Model is
a model of fundamental particles and interactions
he first evidence for the neutrino …
Beta decay
Hadrons are
composite particles made of quarks.
Baryons are …
made of three quarks.
Mesons are
made of quark–antiquark pairs.
bosons are
Force-mediating particles
Force-mediating particles are bosons:
photons (electromagnetic force),
W- and Z-bosons (weak force), and
gluons (strong force)
Difference between electric fields and gravitational fields
The only difference is that two objects with mass will always attract each other.
Charges can either
repel or attract
A charged particle in an electric field will experience …
a force
Rule 1 for electric fields
Electric Field Lines always point from positive to negative.
They follow the path a positive charge would move.
Rule 2 for electric fields
Electric Field Lines always enter and leave the charge perpendicularly.
Rule 3 for electric fields
Electric Field Lines never cross
Rule 4 for electric fields
The closer together the electric field lines
The stronger the electric field
potential difference is …
Potential difference is the number of Joules per Coulomb
Moving charges create ………… ………….. in the ……… ……….. ………. These magnetic fields exert ………… on ……. ……. ……. …….. in the field.
Remember ……… is the flow of electrons
Moving charges create magnetic fields in the space around them. These magnetic fields exert forces on any other moving charge in the field.
Remember current is the flow of electrons
The direction of the magnetic field depends on
the direction of conventional current.
Newton’s laws and relativity equations can’t be applied to atomic, nuclear and sub-nuclear particles. Which branch of physics or theory must be used instead?
Quantum mechanics/ theory
What is the order of magnitude planck length
10 - 35
In which year did geiger and Marsden carry out the gold foil experiment?
In a 1909 experiment, Geiger and Marsden discovered that the metal foils could scatter some alpha particles in all directions, sometimes more than 90°. This should have been impossible according to Thomson’s model. According to Thomson’s model, all the alpha particles should have gone straight through.
What is antimatter
Antimatter is the same as ordinary matter except that it has the opposite electric charge
What is the difference between a positron and electron
The primary difference between an electron and a positron lies in their charge. While an electron carries a negative charge, a positron carries a positive charge. However, they share the same mass and spin, making them antiparticles of each other.
What happens when a particle and its antimatter particle meet
When matter and antimatter collide, the particles destroy each other, with a huge energy release
All particles are classed as either fermions or bosons what is the difference
fermions are the composites of matter
bosons are force carrying particles
What quarks make up a neutron and a proton
Protons contain two up quarks and one down quark. Neutrons contain one up quark and two down quarks.
What holds the quarks together
The strong force
What was the first evidence for the neutrino
The emission of beta radiation provides evidence that neutrons and protons are made up of quarks.
Beta (
) decay is the release of an electron by the change of a neutron to a proton.
P is
proton
n is
neutron
e is
electron
v is
neutrino
_
V
antineutrino
_
e
positron
_
p
antiproton
_
n
antineutron
State the difference between a hadron and a lepton in terms of the type of force experienced by each particle
Leptons are spin 1/2 particles that do not interact via the strong force. The electron, muon, and the electron and muon neutrinos are examples. Hadrons are particles that interact via the strong force.
Give one example of a hadron and one example of a lepton
Proton, Neutron, Antiproton, and Antineutron
Briefly state any differences between the ‘strong’ and ‘weak’ nuclear forces.
strong force has a range of less than 10^-14 m and weak force has a range of less than 10^-17 m
Give an example of a particle decay associated with the weak nuclear force
Beta decay
Which of the 2 forces strong and weak acts over the greater distance
strong force
Describe electric field
Electric fields are set up by charges and show the direction of force on a positive charge
Name the cause of the field for the following
Gravity
Electric
Magnetic
Mass
Charge
Movement of charge
If a charge Q is accelerated by potential V it has ….
work done. W = QV
When an electron moves through a magnetic field it experiences a force. Why?
This is because the movement of the electron is itself producing a field.
The two magnetic fields interact with each other and cause the electron to change direction.
Force on an electron in magnetic field is
perpendicular to motion and the magnetic field
If the charge is moving in the same plane and in either the same or opposite direction to the magnetic field then … what happens?
there is no force acting on the charge (velocity is unchanged)
A charged particle placed in a magnetic field will change direction.
What does this mean
This means it will accelerate without gaining Kinetic Energy.
