Matter and radiation Flashcards
what is the relative charge and mass of a proton?
+1 and 1
What is relative charge and mass of a neutron?
0 and 1
What is the relative charge and mass of an electron
-1 and 1/1840
How are electrons held in the nucleus?
By electrostatic forces of attraction between the nucleus
Definition of an isotope?
Atoms with same number of protons but with a different number of neutrons
What is A and Z for an element
A is the nucleon number and (Total proton and nuetron number) Z is the proton number
What is the specific charge of a charged particle?
Charge divided by mass
Which sub atomic particle has the highest specific charge?
The electron
What is the force that keeps protons and neutrons together?
Strong nuclear force
What is the range of the strong nuclear force. When is it an attractive force and when is it a repulsive force?
Range no more than 3-4 fentometers. Attractive force from 3-4 fm down to about 0.5 fm. Repulsive force with separations smaller than this, to prevent neutrons and protons from being pushed into each other.
What is released in alpha radiation?
An alpha particle, also called a helium particle, of mass 4 and proton number 2.
What is released in beta radiation? When does beta radiation occur?
A beta particle is released. Of mass number zero and charge of -1. It occurs when a neutron in the nucleus changes into a proton.
What else is released in beta radiation as well as a beta particle?
An antineutrino.
Why was existence of antineutrino hypothesised?
To account for conservation of energy in beta decay
What is a photon? What is it’s energy equal to?
A burst of a packet of E.M waves. E=HF, where frequency = c/wavelength
What are three properties which apply to all antiparticles?
They annihilate their corresponding particle if they meet, converting total mass into photons. They have exactly the same rest mass their particle, and also the opposite charge to the particle, if the particle is charged.
What is 1 E.V equal to ?
1.6 times ten the power of minus 19 Joules.
When does annihilation occur?
when particle and corresponding antiparticle meet, and convert their mass energy into radiation energy.
What is produced in annihilation?
2 photons. Minimum energy of each photon produced is E0, which is the rest energy of the particle.
When does pair production occur?
When a photon with sufficient energy passes near a nucleus/electron, it can suddenly change into a particle - antiparticle pair.
What is minimum energy of photon needed?
HFmin = 2E0, so a photon with less energy than this could not create a particle - antiparticle pair.
E.M force between 2 charge particles is due to the exchange of what?
Virtual photons. They are virtual because we can’t detect them directly. They are the exchange particle of the electromagnetic force.
What does an exchange particle transfer?
Force, energy and momentum. Sometimes charge
What are the 4 fundamental forces and what is their order of strengths, from strongest to weakest.
Strong nuclear force, electromagnetic force, weak nuclear force and gravity.
Which exchange particle is associated with the weak nuclear force?
w+ and w- boson. Weak interaction is limited to beta plus and beta minus decay, electron capture, and electron - proton collisions
Which exchange particle is associated with the strong nuclear force?
The gluon
