2.1.3 Particles, Antiparticles and Photons Flashcards
What is electromagnetic radiation?
EM spectrum is a continuous spectrum of all possible frequencies of EM radiation.
- Frequency of a wave is the number of complete waves passing a point per second.
- Wavelength of a wave is the distance between two adjacent crests of a wave.
Name all EM radiation in order of increasing frequency and decreasing wavelength:
EM radiation is split up into 7 different types based on their frequency and properties:
- Radio Waves
- Micro-waves
- Infra-red
- Visible Light
- Ultra-violet
- X-Rays
- Gamma Rays
Higher frequency equates…
The higher the frequency the greater the energy.
What is a photon?
EM waves can only be released and exist in discrete packets called photons.
What is the equation to find the energy carried by one photon?
E = h f
Energy = Planck’s Constant x Frequency of Light
J = (6.63x10^-34) Js x Hz
Relate frequency, wavelength and speed of light into one equation:
f = c / λ
frequency = speed of light / wavelength
Hz = (3.00x10^8) ms^-1 / m
What is an antiparticle?
Each particles has a corresponding antiparticle with same mass and rest energy but opposite charge.
All particles are known as matter and all antiparticles are known as antimatter.
Mass and rest energy of a proton/antiproton?
mass: 1.67(3) x 10^-27 kg
rest energy: 938(.3) MeV
Mass and rest energy of a neutron/antineutron?
mass: 1.67(5) x 10^-27 kg
rest energy: 939(.6) MeV
Mass and rest energy of an electron/positron?
mass: 9.11 x 10^-31 kg
rest energy: 0.51(1) MeV
Mass and rest energy of a neutrino/antineutrino?
mass: 0 kg
rest energy: 0 MeV
What is pair production?
Energy can turn into mass and vice-versa. When energy is converted into mass you get equal amounts of matter and antimatter. It only happens if there is enough energy to produce the masses of the particles. it must always produce a particle and its corresponding antiparticle because certain quantities must be conserved.
What is annihilation?
When a particle meets its antiparticle and all of their masses is converted back into energy in the form of tow gamma ray photons.
How to convert MeV (Mega Electron Volt) into J (Joules)?
Y x 10^6 x 1.6 x 10^-19
What is the minimum rest energy for a pair production?
This is the total rest energy of the particles produced.
As there are 4 particles made from 2 particles:
Emin = 2E0
