Physics

Physics

1. a) radiation~ The spontaneous decay or disintegration of an unstable atomic nucleus accompanied by the emission of radiation.

b) nuclear energy~ Energy released when atomic nuclei undergo a nuclear reaction such as the spontaneous emission of radioactivity, nuclear fission, or nuclear fusion.

c) background radiation~ relatively constant low-level radiation from environmental sources such as building materials, cosmic rays, and ingested radionucleides in the body.

d) nuclear fission~ Atomic nuclear processes which involve the splitting of nuclei with the accompanying release of energy.

e) nuclear fusion~ The nuclear process whereby several small nuclei are combined to make a larger one whose mass is slightly smaller than the sum of the small ones.

2. Two types of nuclear reactions can produce nuclear energy. Nuclear fusion is a process in which two light nuclei combine to form a single heavier nucleus. Nuclear fission is a process in which a heavy nucleus splits into two smaller nuclei.

3. Alpha, Beta, and Gamma radiation is produced when an unstable nucleus decays.

Alpha particles are made of 2 protons and 2 neutrons.

This means that they have a charge of +2, and a mass of 4

Alpha particles are relatively slow and heavy.

They have a low penetrating power - you can stop them with just a sheet of paper.

Because they have a large charge, alpha particles ionise other atoms strongly.

Beta particles have a charge of minus 1, and a mass of about 1/2000th of a proton. This means that beta particles are the same as an electron.

They are fast, and light.

Beta particles have a medium penetrating power - they are stopped by a sheet of aluminium or plastics such as perspex.

Beta particles ionise atoms that they pass, but not as strongly as Alpha particles do.

Gamma rays are waves, not particles. This means that they have no mass and no charge.

Gamma rays have a high penetrating power - it takes a thick sheet of metal such as lead, or concrete to reduce them significantly.

Gamma rays do not directly ionise other atoms, although they may cause atoms to emit other particles which will then cause ionisation.

4. Advantages of using nuclear energy instead of energy produced by fossil fuels:

 The Earth has limited supplies of coal and oil. Nuclear power plants could still produce electricity after coal and oil become scarce.

 Nuclear power plants need less fuel than ones which burn fossil fuels. One ton of uranium produces more energy than is produced by several million tons of coal or several million barrels of oil.