What is meant by radioactivity? (spontaneous) emission (of one or more types of) particles/energy (α / β / γ) In an experiment, the radiation from a radioactive source is passed through an electric field, as shown in the diagram - Leaving Cert Physics - Question 10 - 2014

The experiment demonstrates that radiation can be classified into three types: positive, negative, and neutral. This is evident from the way the radiation interacts with the electric field.

The radiation that is unaffected by electric fields is type 2 (gamma radiation).

The type of radiation that is positively charged is type 1 (alpha radiation).

The type of radiation that is negatively charged is type 3 (beta radiation).

The radiation types in order are: 1) Alpha radiation, 2) Gamma radiation, 3) Beta radiation.

A suitable fuel for nuclear fission is uranium-235 or plutonium-239.

Neutrons play a crucial role in nuclear fission as they initiate the fission process by colliding with the nucleus of fissile material. When a neutron is absorbed by the nucleus, it becomes unstable and splits into smaller nuclei, releasing additional neutrons and energy.

Control rods are made of materials that absorb neutrons, such as boron or cadmium. By inserting or withdrawing these rods from the reactor core, the number of free neutrons in the reactor can be controlled, thus regulating the rate of fission. Inserting the rods increases absorption of neutrons, reducing the fission rate or stopping it completely.

The half-life of iodine-131 is 8 days. After 24 days, which is three half-lives (24/8 = 3), the fraction remaining is calculated as:
rac{1}{2^3} = rac{1}{8}