physics end of unit

definition of half-life

the time it takes for half the amount of radioactive nuclei in a substance to decay

activity is measured in?

becquerels

activity is?

the rate at which a source of unstable nuclei decays

count-rate is?

the number of decays recorded each second by a detector

what is an alpha particle’s range in air

only a few centimetres; can be stopped by a sheet of paper

what does alpha decay do to the mass and charge of the nucleus?

causes both to decrease

what does beta decay do to the mass and charge of the nucleus?

causes the charge to increase but the mass to decrease

radioactive contamination is . . .

the unwanted presence of materials containing radioactive atoms on other materials

irradiation is . . .

the process of exposing an object to nuclear radiation (the object DOES NOT become radioactive)

radiation dose is measured in

sieverts (Sv)

conversion rate for sieverts

1000 mSv = 1 Sv

spontaneous fission is:

rare

usually, for fission to occur, the unstable nucleus must first:

absorb a neutron

carbon-12 and carbon-14 are . . .

isotopes (same number of protons, different number of neutrons)

fuel for nuclear fusion?

hydrogen

fuel for nuclear fission

uranium