Matter and Radiation Flashcards
What does nucleon mean?
A proton or neutron in the nucleus.
What does every atom contain?
A positively charged nucleus comprised of protons and neutrons; and electrons that surround the nucleus.
Define an isotope.
Isotopes are atoms with the same number of protons and different number of neutrons.
Define the specific charge of a charged particle.
The charge of the particle divided by its mass.
Which force holds together the protons and neutrons in a stable nucleus?
The Strong Nuclear Force.
What is the range of the strong nuclear force?
3-4 femtometres which is similar to the diameter of a small nucleus.
Describe when the strong nuclear force is a repulsive force and when it is an attractive force.
From 0-0.5 femtometres the strong nuclear force is repulsive, from 0.5-3/4 femtometres it is an attractive force.
Which equation describes the relationship between frequency and wavelength of electromagnetic waves?
λ=c/f; where λ is wavelength, c is speed of light and f is frequency.
Describe the relationship between the electric and magnetic components of an electromagnetic wave.
They vibrate at right angles to each other and are in phase such that they reach their peaks and troughs at the same time.
Describe annihilation.
A particle and its antiparticle meet and their mass in converted into radiation energy in the form of two photons.
Describe pair production.
A photon with enough energy creates a particle and corresponding antiparticle, and vanishes in the process.
Why are virtual photons so named?
Richard Feynman called them ‘virtual’ because we cannot detect them directly. If we intercepted them with a detector we would stop the force acting and so the photon would cease to be.
Why is the force that causes decay known as the weak nuclear force?
It is known as the ‘weak’ nuclear force because it must be weaker than the strong nuclear force or else it would cause decays in stable nuclei.
Describe W bosons and the role they play.
W bosons are exchange particles of the weak nuclear force which have non-zero rest mass, have a short range of about 1 attometre and are positively or negatively charged. They mediate the exchange in momentum and charge in weak interactions.
Describe electron capture.
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.
