Fig. shows a radioactive source S in a thick lead walled container having a narrow opening. The radiation passes through an electric field between the plates A and B.
a) Complete the diagram to show the paths of α, β and γ radiations.
b) Why is the source S kept in a thick lead walled container with a narrow opening?

(a)When the radiations of radioactive substance are subjected to an electric field, they separate out into the three constituents. Positively charged alpha (α) particles turn towards the negative plate, while the negatively charged beta (β) particles turn towards the negative plate. Uncharged gamma (γ) radiations regains undeflected.
(b)The radiation may cause biological damage. Hence, the radioactive substances are kept in thick lead containers which is an effective radioactive shielding material.