TYPES OF RADIOACTIVITY
There are three main types of radioactivity:
alpha (
a) beta(
b) gamma(
g)
The table shows some of their properties
Property |
Alpha (a) |
Beta (b) |
Gamma (g) |
Range in air |
a few cm |
a few tens of cm |
metres |
Ionising ability |
large |
small |
very small |
Stopped by: |
paper |
mm of aluminium |
cm of lead |
Charge |
+2e |
-e |
0 |
Mass |
8000m |
m |
0 |
Deflection by a magnetic field |
a little |
a lot |
none |
Speed |
<1%c |
90%c |
c |
[m is the mass of the electron - very small, one electron has a mass of about 10
-30 kg!]
(this is an easier way of writing its mass than as 0.000 000 000 000 000 000 000 000 000 001 kg)
[c is the speed of light, 300 000 km/s]
Experiments have identified the three types of radiation as:
Alpha – the two protons and two neutrons (the nucleus of a helium atom)
Beta – high speed electrons
Gamma – very short wavelength electromagnetic radiation
A VERSION IN WORD IS AVAILABLE ON THE SCHOOLPHYSICS USB