Half-Life Flashcards
what is the rate at which unstable nuclei decay measured with
activity and half-life
what is the radiation given out from the nuclei of atoms measured with
a geiger-muller tube and counter
what does the geiger-muller tube and counter do
records count rate which is the number of radiation counts reaching per second
what is radioactive decay in terms of patterns
totally random, so you cant pinpoint which nucleus in the sample will decay and at what time, its a wild beast!
although radioactive decay doesnt have patterns, what can you predict
how long it takes for the radiation emitted by the nuclei to halve known as the half life. all about the time
what can knowing about the life span of a half life allow you to do
radioactive sources arent so unpredictable when you can predict make predictions about them even when its random
what is the activity of a radioactive source
the rate at which the source decays using its half life to figure it out
what is activity measured in
becquerels or Bq (1 Bq = 1 decay per second)
why do radioactive nuclei even decay in the first place
to become more stable
what happens when a radioactive nucleus decays to become more stable
its activity as a whole decreases as old sources emit less radiation, like old people emit less life
tell me son, just how diverse are the lives of nuclei all around the world
some isotopes only need a handful of hours to decay all their unstable nuclei, but some dons can take millions of years
half life sounds like an interesting way to measure decay, but why is this used in the first place and why not full life
because the activity never actually reaches zero, so half lives are used to measure the rate of activity drop off
what is a half life anyway
the time taken for the number of radioactive nuclei in an unstable isotope to be cut in two
so if the definition of the half life is correct, what does the half life also measure
the time taken for the activity and count rate to half with it
ite quick mental logic - a short half life means the activitiy…
falls quickly as the nuclei are unstable and rapidly decay
why are sources with tiny half lives dangerous to be around
they emit a high level of radiation in their youth, but they quickly become safe and old
even more mental logic - a long half life means the activity…
falls slowly obviously because most of the nuclei dont decay for a long time… just kinda sits there… releasing small amounts of radiation for a long time… dead life
why can a source with a ling half life be dangerous as well
because the release of radiation for a long time exposes nearby areas to radiation for millions of years, not healthy mate
quick maths - the initial activity of a sample is 640 Bq. calculate the final activity as a percentage of the initial activity after 2 years
1 half life = 640 / 2 = 320
2 half life = 320 / 2 = 160
160 / 640 = 0.25
0.25 x 100 = 25%
in a graph of activity against time (activity on y and time on x), how will the line be shaped
an inside drooping slide from the top of the activity down to time
how do you find the half life from a graph of activity against time
finding the time interval on the bottom axis corresponding to halving of the activity on the vertical axis (like a median in a cumilative frequency graph)
what does the tube and the counter do in the gieger muller tube and counter
- the gieger muller tube clicks every time it detects radiation
- the counter displays the number of clicks per second
what does the tube and the counter do in the gieger muller tube and counter
- the gieger muller tube clicks every time it detects radiation
- the counter displays the number of clicks per second
