Question

How can we prove that $\alpha$− rays possess positive charge and $\beta$− rays possess negative charge ?

Answer 1

There are three main types of radiation which include alpha ($\alpha$), beta ($\beta$) and gamma ($\gamma$) rays. They majorly differ in energy, mass and how deeply they are able to penetrate people or objects.

Complete answer:
- An $\alpha$- particles is positively charged as it is actually the nucleus of the Helium-4 atom. $\alpha$-particle is basically made up of neutrons and two protons from the nucleus of an atom. $\alpha$-particles are generally formed during the decay of especially the heaviest radioactive elements, like radium, uranium, and polonium.
- On the other hand $\beta$- particles are the high energy electrons. These particles are actually not the electrons from the electronic shells around the nucleus, rather they are generated during the splitting of the neutron in the nucleus in order to form a proton and an electron. Thus, $\beta$-particles are negatively charged. While, $\gamma$rays are not associated with any electrical charge.
- In order to identify the charge that is present on the radiations, the emissions from any radioactive substance are made to pass through an electromagnetic field. You will observe that the rays deflected towards the negative plate are $\alpha$-rays which means $\alpha$-rays possess a positive charge. On the other hand, you will observe that the rays deflected towards the positive plate are $\beta$-rays which means that $\beta$-rays possess a negative charge.

Note:
$\alpha$- rays consist of helium nuclei and can be readily stopped by a paper sheet. $\beta$-rays comprise of electrons or positrons, and can be stopped by a thin aluminium plate but $\gamma$-rays generally require a shielding by a dense material like lead, or concrete.