physics flashcards
what is the plum pudding model?
a ball of positive charge with negative electrons embedded.
Why use gold foil during alpha scattering experiment?
because we can hammer Gold into foil.
What was the observation during the alpha scattering experiment?
most alpha particles went through the foil without changing direction
What was the plum pudding model changed into?
nuclear model
What do radioactive isotopes release from the nuclear of their atoms?
radiation
decay is a .... process (fill the blank)
random
define half life
time it takes for the number of nuclei to decay.
define count rate
number of decays per second
define irradiation
exposing an object to nuclear radiation
What precautions can you take for irradiation?
sheilding( wearing gloves against alpha, lead apron)
monitoring
define contamination
unwanted radioactive isotopes end up on other materials
what is the ionising power of alpha,beta and gamma
alpha: strongly ionising
beta:quite ionising
gamma: weakly ionising
what is an alpha particle?
consists of 2 protons , 2 neutrons
what is a beta particle?
an electron ejected from the nucleus
what is a gamma ray
a type of electromagnetic radiation
what is the range in air for alpha,gamma and beta particles in air?
alpha: 5cm in air
beta: 15cm in air
gamma:several metres in air
what is the penetrating air for alpha,gamma and beta?
alpha:single sheet of paper
beta: few cm of aluminium
gamma: several cm of lead
what is ionising power?
when radiation collides with atoms. that can cause the atoms to lose electrons and form ions
in nuclear fission, the nucleus...
splits
What needs to happen for fission to take place?
the nucleus has to absorb a neutron
what happens when a nucleus splits?
it forms 2 smaller nuclei roughly equal size
what does the nucleus emit when it splits?
2 or 3 neutrons,gamma radiation and energy
all of the fission produts have .... energy ( fill the blank)
kinetic
what is a controlled reaction used for?
to release energy in a nuclear reactor
define nuclear fission
a large nucleus splits into 2 smaller nuclei usually by absorbing a neutron
nuclear fusion is when...
2 light nuclei are joined to form a heavier nucleus
define nuclear fusion
the process by which energy is released in stars