Figure shows a radioactive source S in a thick lead walled container having a narrow opening. The radiations pass 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?

(c) Name the radiation which is unaffected by the electrostatic field.

(d) Which radiation is deflected the most. Give reason.

(e) Which among the three radiations causes the least biological damage?

(a) Below diagram shows the paths of α, β and γ radiations:

(b) The source S is kept in a thick lead walled container with a narrow opening so that the walls of the container absorb the radiations which strike on them from the inside and thus radiations only come out through the narrow opening.

(c) γ radiation is unaffected by the electrostatic field.

(d) The β radiation is deflected the most.
α particle is a helium nucleus consisting of two protons and two neutrons. Beta particles are fast-moving electrons with a very low mass. α particles are heavier than β particles so β particles have a high charge to mass density as compared to α particles. Due to this reason, β particles are deflected much more than the α particles.

(e) α radiation causes the least biological damage.