Physics Topic 7 revision
characteristics of the strong force
-acts over short distances (nucleus) -very strong -caused by internuclear repulsion of protons -mediated by gluons
Characteristics of Weak nuclear force
-acts over short distances (nucleus) -weak -includes lighter and heavier particles these particles are electrons, positrons, neutrinos, neutrons -mediated by W+, W- and Z0
Electromagnetic force
-involves charged matter -either attractive or repulsive -range is infinite -relatively strong -mediated by photons
# of quarks in a meson
2 (1 quark and 1 anti-quark)
# of quarks in a baryon
3 (all of 1 charge, either all positive or all negative)
definition of binding energy
amount of energy released when a nucleus is assembled from the component nucleons (comes from decrease in mass)
which particles go back in time in feynman diagrams
antiparticles
characteristics of gravitational force
attractive range is near infinite -quite weak force -mediated by gravitons
deflection of beta particles
behaves like a negative charge
deflection of alpha particles
behaves like a positive charge
what are artificial transmutations
bombarding a nucleus with a nucleon or another small nucleus
Equation of Radioactive decay
dN/dt (is proportional to) -N where N is the number of atoms of the element
where do beta particles originate
from the nucleus, result from a neutron decaying into a proton and a negative beta particle (and an antineutrino
when is a reaction energetically feasible
if the products have a HIGHER BINDING ENERGY than the reactants.
what are subgroups of hadrons
mesons and baryons, bosons
Do neutrinos have charge
no
can quarks be isolated?
no, they exist in 2s or 3s
deflection of gamma particles
not deflected
beta plus decay
proton decays into neutron and a positron. also emits a neutrino
what are examples of elementary particles
quarks, leptons and exchange particles
example of the nuclear fusion
sun:
What is the mass defect
the difference between the mass of an isotope and its mass number.
what happens if an electron and a positron meet
they annihilate producing 2 gamma rays
what makes hadrons special
they are composite particles, are a combination of quarks
What happens to most of the alpha particles
they go straight through the gold foil
why are gamma rays important
they result in the nucleus having less energy as the particle goes to a lower energy state
definition of half life
time taken for half the number of nuclides present in a sample to decay
neutron quark configuration
u d d
proton quark configuration
u u d
which force can cause quarks to change their type
weak interaction
