Higher Physics Particles and Waves

what is one order of magnitude difference?

is x10 by size (two orders is by x100)

fundamental particle

is a particle not composed of any other other particles

what are the 12 fundamental particles called?

fermions

two types of fermions

(6)quarks and (6)leptons

what are the 6 quarks?

-up

-down

-charm

-strange

-top

-bottom

what are the 6 leptons?

-electron

-electron neutrino

-muon

-muon neutrino

-tau

-tau neutrino

what are the 4 force carriers known as 'force mediators' called?

gauge-bosons

fundamental partciles table

ALL the fundamental particles have corresponding ______________

antiparticles

antiparticles

have the same rest mass as the particles but the opposite charge

first antiparticle to be discovered?

the positron

what happens when a particle and its antiparticle meet?

they will annihilate each other and their combined mass is converted into energy

hadrons

are particles made from quarks that are held together by the strong force

two types of hadron

baryon and meson

what are baryons?

made up of three quarks or three antiquarks (known as anti baryons)

what are mesons?

made up of a quark and an antiquark

baryons and mesons can only have whole _____________ charges

integer

leptons have no size and in most cases low or __ mass

no

there are __________ generations of leptons, only electrons occur in ordinary mass. muons occur in the upper atmosphere and tau only seen in lab experiments

three

what are the four forces particles may experience?

-strong (nuclear) force

-weak (nuclear) force

-gravitational force

-electromagnetic force

gauge boson for strong force

gluon

gauge boson for weak force

W and Z bosons

gauge boson for gravitational force

gravitation

gauge boson for electromagnetic force

photon

when can beta decay occur?

in an unstable nuclei where the nucleus emits an electron, leaving the nucleus with the same mass number but an increase in atomic number of 1

(beta decay) mass number is conserved the actual mass of the proton is less than the mass of the neutron, this decrease in mass results in a release of energy, available as _________ energy to the electron

kinetic

evidence for neutrino

momentum was not conserved, so concluded that another particle must be emitted, first evidence for neutrino was beta decay

electric field

is a region where a charged particle (i.e. proton or electron) experiences a force. If the charged particle is free to move, it will accelerate in the direction of the unbalanced force

electric field of isolated positive charge

positive test charge would experience a repulsive force

electric field of isolated negative charge

negative test charge would experience a attractive force

________ __ _____ when a charge is moved in an electric field

work is done

(for negative charge) to move an electron towards the negatively charged plate, energy is needed. the work done is gained by the electron as ____________ _____________ _________

electrical potential energy

(for negative charge) if electron is free to move back towards positively charged plate, electric field does work on the electron. electrons electrical potential energy is changed into _________ ________ as the electric field accelerates electron towards positive plate

kinetic energy

potential difference

the energy required to move one coulomb of charge between two points in the electric field

work done equation

Ew = Q x V

equation to work out speed of the charged particle after it has passed through the electric field

Ew by field = Ek gained by particle

Q x V = 1/2 x M x V2

v = √(2QV/m)

if the charged particles enters the field with an initial speed then its _________ _________ _________ must be added to kinetic energy gained in the field.

initial kinetic energy

magnetic fields are produced by _____________ __________

moving charges

right hand rule physics

WITH RIGHT HAND (opposite for protons)

in particle accelerators ____________ _______ are used to accelerate the charged particles

electric fields

in particle accelerators _______________ _________ are used to deflect the charged particles

magnetic fields

in cyclotron (particle accelerator) why is an AC supply used?

as it needs to be AC so you can always attract the particle to the opposite side

how does a cyclotron work?

ions are injected at point near the centre. AC potential difference between the 'dee' shaped electrodes accelerate the particles. a magnetic field causes the particles to move in a circular path. when particle crosses from one dee to another it accelerates. after each acceleration the particles moves to a slightly larger orbit. then extracted once it reaches the outer edge.

in a magnetic field, the mass of electron is smaller than proton so it _________ sooner

curves

what was Ernest Rutherford experiment?

alpha scattering experiment form gold foil, done in a vacuum as the alpha particle would be absorbed by air

internal structure of atoms (from Ernest exp)

-most of the atom is empty space (since most alpha particles passed straight through)

-most of the mass of an atom is concentrated in a very small central area

-the nucleus is positively charged (repels positive alpha particles)

nuclide notation

isotope

different mass numbers but same atomic number, same number of protons but different number of neutrons

alpha decay

the mass number of new atom is four less than the original. the atomic number is two less than the original

beta decay

the mass number of new atom is the same as the original. the atomic number increased by 1

when does beta decay take place?

when a neutron in the nucleus splits into a proton and an electron. the proton stays in the nucleus while the electron is ejected from the atoms nucleus

gamma decay

when gamma rays are ejected form an atoms nucleus, this does not change the mass number or atomic number of the atom. it only changes the energy state of the nucleus

what are gamma rays?

are photons of electromagnetic energy- they are not particles

what happens during nuclear fission?

a large atomic nucleus splits into 2 small nuclei and sometimes several neutrons. the smaller nuclei and neutrons produced gain large amounts of kinetic energy.

two types of nuclear fission?

- spontaneous, large atomic nucleus splits up by itself at random

- induced by neutron bombardment, a neutron is fired at the nucleus, causing it to split

total mass before a nuclear fission reaction is __________ than total mass after (related to Einsteins equation)

greater

nuclear fission can be ____________ i.e. in a nuclear reactor or can be uncontrolled i.e. in nuclear weapons

controlled

what happens during nuclear fusion?

2 small atomic nuclei combine to form a larger nucleus. the larger nucleus and other particles produced (i.e. neutrons)gain large amounts of kinetic energy

in nuclear fusion, two small mass nuclei combine to larger mass, but the total mass before is ____________ than total mass after

greater

extremely high ______________ are required for this fusion reaction to occur

temperatures

what happens to the reactant molecules in these high temperatures for nuclear fusion?

they loose their electrons and become positively charged. refer to this as plasma

an example of where nuclear fusion takes place

in stars, like the sun

the lost mass in both nuclear fission and fusion reactions is converted into ____________ ________ of the products

kinetic energy

coolant for nuclear fission

cooling system involves the thermal energy produced by the fission reaction being transferred away from reactor into a conventional steam generator/ turbine combination to generate electricity.

coolant and containment issues for nuclear fusion

extremely high temperatures of the plasma required for fusion means a strong magnetic field is necessary to contain the plasma.

where is reactor for nuclear fission contained?

housed in a containment vessel consisting of concrete of lead to prevent escape of radioactive material and nuclear radiation

wave theory

electromagnetic energy (i.e. light) behaves as a continous wave. Meaning it can be reflected, refracted and diffracted. It can produce _______________

interference

light emits properties of both a wave (interference) and a __________ (photoelectric effect)

particle

quantum theory

electromagnetic energy is a stream of tiny, individual "wave packets" called quanta or photons.

however in quantum theory the energy of a photon does not depend on its amplitude. the energy is directly proportional to its _______________.

frequency

what is evidence for the theory of quantum physics?

the photoelectric effect

work function

is the minimum energy which must be supplied to enable an electron to escape from the metal surface.

photoelectric effect

one photon of eletromagnetic energy strikes a metal surface, it causes one electron to be ejected from the metal surface if the photons energy, hf, is greater or equal to the work function of the metal. part of photons energy is being used to enable the electron to escape, the rest is given to the emitted electron as kinetic energy.

threshold frequency

a photon must have a minimum energy equal to the work function of a metal and hence a minimum frequency to release an electron from the metal surface.

each metal has its own unique threshold _______________

frequency

what happens when hf is greater than the work function ?

electron is ejected

what happens when the hf is less than the work function?

no electron is ejected

____ photon transfers its energy to one electron. the ejected electrons can be reffered as 'photoelectrons'

one

photoelectric effect diagram

how is a photoelectric current produced?

the emmited electrons experince an unbalanced force and accelerates towards the postively charged plate. An electric current is thus created in the circuit.

photoelectric current and irradiance of the radiation are ____________ proportional

directly

electromagnetic waves consist of a _______________ that transmits energy in the form of varying electric and magnetic fields

disturbance

electromagnetic spectrum

definition for interference:

is the test for a wave, in order to prove that any form of energy moves as a wave, an interference pattern must be shown

two types of interference?

constructive and destructive

constructive interference

when 2 wave crests or 2 wave troughs arrive at the same point at the same time, they are in phase. the superposition of these two waves results in a stronger signal

destructive interference

when a wave crest and a wave trough arrived at the same point at the same time, they are out of phase. the superposition of these two waves casues the signals to cancel each other out or reducing the amplitude of combined wave

constructive and destructive interference for water waves

at points of constructive the water wave has a maximum amplitude. at points of destructive interference the water appears calm.

constructive and destructive interference for sound waves

at points of constructive interference a loud sound can be detected. at points of destructive interference a quiet sound can be detected.

constructive and destructive interference for light waves

at points of constructive interference, bright fringes are observed. at points of destructive interference dark fringes are observed.

maxima

the points of maximum disturbance where the waves are completely in phases and constructive interference occurs

minima

the points of minimum disturbance where the waves are completely out of phase and destructive interference occurs

if 2 waves are coherent, they have the same frequency, wavelength and velocity and have a ___________ phase relationship

constant

what must be used in order to achieve coherent waves and interference patterns?

a single source must be used to produce the 2 waves

maxima number order

central maxima m=0

first order maxima m=1

second order maxima m=2

minima number order

first minima m=0

second minima m=1

third minima m=2

(No central maxima)

diffraction grating for the interference of light

light is diffracted through each slit, causing constructive and destructive interference. either monochromatic light or white light can be used.

a grating doesnt just result in diffracion of light, it results in more sources of light which create an _____________ _________

interference pattern

how to calculate the slit separation

d = 1 x 10-3 /number of lines per mm