Kind: captions
Language: en
At the end of the 1800s, physicists were
staggered to find there was radiation
coming out of all kinds of things, just
dirt and rocks. Uh the very first time
this was discovered was with a jar of
uranium salts that was left in a drawer
overnight. And in the morning, uh a
photographic plate that was next to it
had been exposed even though it had been
in the dark all night. So where had the
radiation came from? From this stuff,
uranium salt. It was so to discover that
dirt was giving out radiation. There was
worse in store. They discovered that
there were three different types of
radiation going on. Uh so they really
had no idea what was what was happening.
Um so what do you do as a scientist? You
name it. So they named it A radiation, B
radiation, C radiation. Well, that's a
bit dull really, isn't it? So maybe
let's go for something more sciency.
Alpha, beta, gamma. Yeah, that's much
better. I've got an example here. I've
got uh some alpha, beta, and gamma
radiation. Uh gamma sources here. I also
have a Geiger counter, which is uh a
little device that gives off a click
when it detects radiation. So, I can
hold it over the source. You can hear
you get a lot of clicks.
So, what are the different types? So our
alpha it turned out
pretty much completely blocked by
paper
whereas the beta
and the gamma
makes basically no difference. So if we
try lead
our alphas are completely blocked
strontium
the beta is pretty much blocked
but our gamma source
it makes basically no difference. So, we
can even go to a thick solid piece of
lead.
And you can still see some things are
getting through there.
Um, so we could try.
There's a bit penetrating through.
So, but I think I must be thicker than
lead. So, what are our three types of
radiation? Science. Scientists
eventually worked out that the alpha
radiation is matter. So it's two
protons, two neutrons. That's the
nucleus of helium.
Uh the beta source gives out electrons
and the gamma source gives out
electromagnetic radiation.