Particles and Waves Flashcards
What is a fundamental particle?
A particle that can’t be divided further
What are protons and neutrons made of?
Quarks
What is a fermion?
A particle of matter
Leptons and Quarks
What classifications of Quarks are there?
1st Generation : Up, Down
2nd Generation : Strange, Charm
3rd Generation : Top, Bottom
Where are each generation of Quarks found?
1st Generation - make up our normal universe. Found in protons and neutrons
2nd and 3rd Generations - Found in high energy collisions in particle accelerators or cosmic rays
What is the charge on an Up Quark?
+2/3
What is the charge on a Down Quark?
-1/3
Remembering the table of Quarks and Leptons, what was in the top row and what was their charges? Include their symbols as well.
Up (u), Charm (c), Top(t)
All +2/3
Remembering the table of Quarks and Leptons, what was in the second row of Quarks and what was their charges? Include their symbols.
Down (d), Strange (s), Bottom (b)
All -1/3
Remembering the table of Quarks and Leptons, what was in the top row of the Leptons and what was their charges? Include their symbols.
Electron (e), Muon (μ), Tau (T)
All -1
Remembering the table of Quarks and Leptons, what was in the bottom row of Leptons and what was their charges? Include their symbols.
Electron neutrino (Ve), Muon neutrino (Vμ), Tau neutrino (VT) All 0
How do you change a particle into an antiparticle?
Same mass
Change the sign of the charge
What is the antimatter version of a Up Quark?
Anti-Up
-2/3
What are Hadrons?
Heavy particles made up of groups of quarks
What are the two types of Hadrons?
Baryons
Mesons
What determines what type of Hadron a particle will be?
How many quarks making up the particle
What are the two types of baryons and what are they made of?
Protons = two up quarks and a down quark = +2/3 +2/3 -1/3 = +1 Neutrons = two down quarks and one up quark = -1/3 -1/3 +2/3 = 0
What are Mesons made of and give an example?
Made from a quark and an anti-quark
e.g. negative pion = anti-up quark + down quark = -2/3 -1/3 = -1
What is the hierarchical path of particles?
Fundamental Particle (Quarks and Leptons) -> Hadrons (Baryons and Mesons)(Protons and Neutrons
What are the four fundamental forces?
Gravitational
Electromagnetic
Weak Nuclear
Strong Nuclear
What fundamental force is related to a Graviton and what does it do?
Gravitational Force
Weakest Force
Holds matter together in planets, stars and galaxies
What fundamental force is related to a Photon and what does it do?
Electromagnetic Force
Is a combination of electrostatic and magnetic forces
Holds electrons within atoms
What fundamental force is related to W and Z and what does it do?
Weak Nuclear Force
Involved in radioactive beta decay
Present in lepton-quark interactions
What fundamental force is related to a Gluon and what does it do?
Strong Nuclear Force
Holds protons together in the nucleus of an atom
Only experienced in quarks
What evidence is there for neutrino’s?
Beta decay
On electric field diagrams, what way do the arrows point?
Positive to negative
The path a proton would travel
What are the three types of electric fields that we can draw? How do we draw them?
Single charge - circle with the charge in the middle, lines coming out of circle. If positive, arrows point away. If negative, arrows point into centre
Double charges - Same as above. If both are positive or both are negative, lines will repel one another. If unlike charges, lines will connect, positive attracted to negative
Electric field - positive bar and negative bar. Draw lines between the two. Arrows from positive to negative
What does it mean if the lines in an electric field are close together?
The field is stronger
What will deflect first in an electric field : a electron or an alpha particle?
The electron as light particles deflect faster
Why don’t gamma rays and neutrons deflect in an electric field?
Have no charge
How do you calculate the work done on a particle when moving through an electric field?
Ew = QV Ew = Ek QV = 1/2mv^2
Give examples of practical uses of electric fields?
Spray Painting
Cleaning ash from exhaust gases
Using the weird finger thing, what does the thumb represent?
The motion of the electron - the way it will move
Using the weird finger thing, what does the index finger represent?
The field direction
Using the weird finger thing, what does the middle finger represent?
The electron flow/current
Use right hand for negative charges and left hand for positive charges
What ways can the electrons go?
Into the page/down
Out of the page/up
left
right
What way is the electric field going if it shows a cross?
Away from you
What way is the electric field going if it is shown by a dot?
Towards you
What is the purpose of particle accelerators?
Increase the velocity of particles to get them to collide which will break them into fundamental particles - research
Can be used to treat cancer
What are the main types of particle accelerators?
Linear accelerators
Cyclotrons
Synchrotrons
Why do linear accelerators and cyclotrons use an alternating current?
To keep the particles moving in the correct direction
Give an advantage and a disadvantage of linear accelerators
Advantage - simple acceleration
Disadvantage - must be very long to accelerate particles to high energy states
How are charged particles kept in the centre of a synchroton?
Magnets
How do cyclotrons work?
Spiral shape
Charged particles start off in the centre and spiral to the outside for use through electric fields and ‘dees’ (electrodes)
Particles get faster with each dee they pass , giving them a greater orbit
How is the collision of particles picked up?
Through detectors
What causes the acceleration of charged particles in a particle accelerator?
Electric fields
What is the atomic number?
The number of protons/electrons
What is the relative atomic mass number?
Number of protons + Number of neutrons
How would you work out the number of neutrons an atom had?
Mass number - atomic number(no of protons)
What are isotopes?
Atoms with the same atomic number but a different mass number
What is alpha decay?
When an atom loses a helium nucleus (two protons and two neutrons)
What happens to an atom when it loses an alpha particle?
Mass number decreases by 4
Atomic number decreases by 2
New element is corresponding to new atomic number
What is beta decay?
When a neutron changes into a proton and electron. The electron and an anti neutrino are emitted.
What happens to an atom when undergoing beta decay occurs?
Gains a proton so therefore the atomic number increases by one
How does an atom differ when it emits gamma rays?
Not at all
Are photons of electromagnetic radiation, not particles, so therefore don’t alter the mass no. or the atomic no.
What are the two types of nuclear reactions?
Fission
Fusion
What are the two types of fission reactions?
Spontaneous
Stimulated
What happens during Spontaneous Fission?
A large atomic nucleus splits into two smaller nuclei, releasing neutrons and energy
What happens during stimulated fission?
A neutron is fired, splitting a large nuclei into two smaller nuclei and releasing energy, as well as three additional neutrons that can cause further fissioning.
Give a brief summary of what occurs in a nuclear reactor
Fission occurs (stimulated) Released neutrons move fast so graphite rods are used to slow them down so they hit other atoms to cause further fissions Control rods (boron) absorb some loose neutrons to keep the reaction under control The energy released heats the reactor core Coolant fluid turns into steam which drives turbines
What happens during a fusion reaction?
Two light elements combine to form a heavier elements releasing large quantities of energy
Why is mass lost during nuclear reactions?
Is converted into kinetic energy
E = m c^2
How do you calculate the energy released during a nuclear reaction?
Calculate the mass of the left hand side of the equation
Calculate the mass of the right hand side of the equation
Calculate the loss in mass (left-right)
E = m c^2
What is h the symbol for?
Planck’s constant - in databook
6.63x10-34 Js
What is the photoelectric effect?
The emission of electrons when light hits a material
What is a photon?
A light particle
How do you show the difference between a particle and an antiparticle?
Put a bar on top of the symbol for antiparticles
How does the photoelectric effect support quantum theory?
Electrons from within the metal are being given enough energy to be released from the surface of the metal
What is threshold frequency and what is its symbol?
The minimum frequency of electromagnetic radiation required in order to eject electrons from the surface of a metal
fo
What is the work function?
The minimum energy required to release an electron from the surface of a metal.
Eo
How do you calculate the work function?
Eo = hfo
measured in joules (J)
What formula is to be used when the energy supplied to the metal is greater than the work function?
Ek = E - Eo
so the kinetic energy of the particle being released is equal to the energy being given take away the energy required to release the particle
Can be re-written as:
1/2mv^2 = hf - hfo
What is irradiance?
The strength of the radiation
How do you calculate the distance between slits on a grating?
Scale number up to a metre
(e.g. 300 slits per mm = 300,000slits per metre)
distance between slits = 1/no. of slits
(e.g. 1/300,000 = 3.33x10-6 m)
How do you work out the angle between the screen and the maxima?
tan theta = distance between maxima / distance between maxima
How do you compare things in order of magnitudes?
Take the values away from one another and find the closest order of magnitude.
Answer will be e.g. 2 orders of magnitude
What does it mean when waves are in phase?
Waves are vibrating in the same way, at the same time
What does it mean is waves are out of phase?
Waves are vibrating in exact opposite ways, at the same time
What does it mean when sources are coherent?
Waves have the same frequency, same wavelength, same velocity
What is constructive interference?
When two waves in phase with each other meet, forming a double wave
What is destructive interference?
When waves meet out of phase and cancel each other out
How can you show interference?
Allow waves from one source to through two narrow slits in a barrier.
Can be done with water waves in a ripple tank
What is interference?
When two or more waves meet, forming one wave form
When looking at the inference of light, what does it mean when when a bright fringe is shown?
Light arrives in phase and is an area of constructive interference
When looking at the interference of light, what does it mean when a dark fringe is observed?
The light arrives out of phase and is an area of destructive interferene
What increases the spacing of lines of interference?
Decreasing the separation of the sources
Increasing the wavelength/Decreasing the wavelength
Observing interference pattern at an increased distance from the sources
When does constructive interference occur?
When path difference = m x lambda
Where m is an interger
When does destructive interference occur?
When path difference = (m + 1/2) x lambda
What is a maxima?
The interference pattern of a constructive wave
What is a minima?
The interference pattern of a destructive wave
Why is the central maxima the strongest wave?
Because the waves from both sources have to travel the same distance
What is the grating equation?
dsino = m x lambda
How would you measure the wavelength of a laser light?
Measure the distance between the maxima (d)
Measure distance from grating to the screen (D)
Use tan theta = d/D to find theta
Calculate the distance between slits in grating
Use m lambda = d sin o to find wavelength
How would you calculate the distance between slits?
Multiply to calculate how many slits per metre
distance between slits = 1/slits per metre
(e.g. 300 slits per mm –> 300,000 per metre –> 1/300000 –> 3.33x10-6m)
What is the charge on an electron?
1.6 x10-19
What is refractive index?
A measure of how much light is slowed down in a material
What is the symbol for refractive index?
n
Describe the motion of light as it enters and exits a glass block
Slows down as it enters
Speeds up as it exits
When does light change direction?
When it meets a (glass) block at an angle
When does light not change direction?
When it meets the face of the block perpendicular (at a right angle)
What happens when light enter a optically denser material?
Velocity decreases Wavelength decreases (corridor analogy) Frequency remains constant
What has a shorter wavelength : red or blue light?
Blue
What determines the refractive index?
The frequency
Why is ROYGBIV expressed when light enters a prism?
The refractive index is dependant upon frequency
Monochromatic light is made up of different frequencies
When the light is passed through the material, the frequencies are all slightly refracted differently causing the colours to spread out (diverge)
What is photoemmission?
Electrons being emitted from a metal surface when struck by electromagnetic radiation
