Question

state two ways it is possible to distinguish in a laboratory between alpha and beta radiation

Answer 1

1) Alpha radiation can be stopped by thin sheets of paper or even few cm of air.

2) Beta radiation can be stopped by few mm of metallic (aluminium) sheet.

3) The alpha radiation is positively charged (2 unit positive charge) having 2-protons and 2-neutrons; It is usually considered a helium nucleus, It has mass of approx. 4 a.m.u.

4) Beta radiation is negatively charged and has mass equivalent to that of an electron.

Thus, the simplest way to distinguish between alpha and beta particle is to measure the count by putting either thin sheet of paper or a metallic foil (few mm thick) between a counter and the radiation source. Depending upon the count of the counter we can easily detect that the radiation is an alpha or beta particle.

Both the particles make impact on photographic plates.

Let us assume that we place a metallic plate having positive and negative charges over it and a source is kept opposite to the photographic plate. If the stream of radiation is deflected towards negative plate end then it is alpha particle radiation and if the radiation is deflected towards positively charged plate then it is beta radiation.

Moreover, ionization chambers give a hint towards whether a particle is alpha or beta. Ionization chamber contains gas which is easily ionized by alpha radiation. Beta radiation does not produce enough ionization and hence cannot be detected using ionization chamber.