Particles and Radiation Flashcards
Charge of a proton
+ 1.6 x 10^-19 C
Charge of an electron
- 1.6 x 10^-19 C
Proton rest mass
1.673 x 10^-27 kg
Neutron rest mass
1.675 x 10^-27 kg
Electron rest mass
9.11 x 10^-31 kg
Specific charge
Charge / mass
Isotopes
Atoms with the same number of protons and different numbers of neutrons.
Proton number / Atomic number / Z
Number of protons in the atom.
Nucleon number / Mass number / A
Total number of protons and neutrons in an atom.
Strong Nuclear Force
Acts between nucleons. Attractive between 3-4 fm and 0.5 fm. Repulsive for distances smaller than 0.5 fm.
Alpha radiation
Consists of alpha particles which are comprised of two protons and two neutrons. Highly ionising, can be stopped by paper.
Beta radiation
Consists of fast moving electrons. Stopped by aluminium.
Gamma radiation
Electromagnetic radiation emitted by an unstable nucleus. Has no mass or charge and can pass through thick metal plates but is stopped by lead. Emitted by a nucleus with too much energy, following an alpha or beta emission.
Beta minus decay
A neutron in the nucleus changes into a proton, a beta particle is created in the nucleus and is emitted along with an antineutrino.
Wave speed equation
𝑐 =𝑓 𝜆
Wavelength range of radio waves
Larger than 0.1 m
Wavelength range of microwaves
1 mm to 0.1 m
Wavelength range of infrared
700 nm to 1 mm
Wavelength range of visible light
400 nm to 700 nm
Wavelength range of ultraviolet
1 nm to 400 nm
Wavelength range of X-rays
0.001 nm to 10 nm
Wavelength range of gamma rays
Less than 1 nm
Electromagnetic waves
Emitted by a charged particle when it loses energy for example when a fast moving electron is stopped, slows down or changes direction or when an electron in a shell of an atom moves to a different shell of lower energy. Consists of an electric wave and a magnetic wave which travel together in phase at right angles to eachother and the direction they are travelling.
Photons
Packets of electromagnetic waves.
Photon energy equation
E = h f
Planck’s constant, h
6.63 x 10^-34 Js
Power of a laser beam
n h f, where n is the number of photons in the beam passing a fixed point per second.
Antiparticles
There is a corresponding antiparticle for every type of particle that annihilates the particle if they meet, converting their total mass into photons and has exactly the same rest mass and opposite charge to the corresponding particle.
Electron volt
The energy transferred when an electron is accelerated through a potential difference of 1 volt.
Annihilation
Occurs when a particle and a corresponding antiparticle meet and their mass is converted into radiation energy. Two gamma ray photons are produced in this process.
Pair production
Occurs when a photon with sufficient energy passing near a nucleus or an electron suddenly changes into a particle-antiparticle pair and vanishes. Only gamma ray photons have enough energy for pair production.
Exchange particles for the electromagnetic force
Virtual photons.
Exchange particles for the weak nuclear force
W bosons.
W bosons
Have a non-zero rest mass, have a very short range of no more than about 0.001 fm and are positively charged or negatively charged.
Weak Nuclear Force
Acts on all types of particles.
Examples of the weak interaction
Beta minus decay, beta plus decay, electron capture, neutrino interacting with a neutron and making it change into a proton with a beta minus particle being created and emitted and an antineutrino interacting with a proton making it change into a neutron with a beta plus particle being created and emitted.
Beta plus decay
A proton in the nucleus changes into a neutron, beta plus particle and neutrino are emitted, W+ exchange particle.
Electron capture
Occurs when a proton in a proton-rich nucleus turns into a neutron as a result of interacting through the weak interaction with an inner-shell electron from outside the nucleus. The W+ boson changes the electron into a neutrino. Can also happen when a proton and an electron collide at very high speeds.
Exchange particles for the strong nuclear force
Gluons
Strong nuclear force
Affects hadrons only, has a range of between 0.5 fm and 3 fm. Repulsive for distances below 0.5 fm.
Muons, μ
Heavy electron with a rest mass of over 200 times the rest mass of the electron. Negatively charged, decays into an electron and an antineutrino.