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Gamma radiation would not be blocked by a thin sheet of aluminum.

This Physics quiz is called 'Radioactivity - Atoms and Radiation' and it has been written by teachers to help you if you are studying the subject at senior high school. Playing educational quizzes is one of the most efficienct ways to learn if you are in the 11th or 12th grade - aged 16 to 18.

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Radioactive substances emit radiation from the nuclei of their atoms all the time, this is called radioactive decay. These nuclear radiations can be very useful but may also be very dangerous. At the surface of the Earth, there is a constant background radiation which comes from a variety of sources, including gasses in the air, radioactive substances in the rocks, fallout from nuclear explosions and accidents at nuclear power stations, and also from space (cosmic radiation and radiation from the Sun).

To understand what happens to radioactive substances when they decay we need to understand the structure of the atoms from which they are made.

The model of an atom that we use to teach at senior high school was developed in the early part of the twentieth century. At the center of the atom is the nucleus; this occupies only a very tiny volume of the whole atom. The nucleus is made up from protons and neutrons that are bound together by nuclear forces. The protons are said to have a mass of 1 atomic mass unit and a small electrostatic charge of +1. Neutrons are electrically neutral and also have a mass of 1 atomic mass unit. The nucleus therefore has an overall positive electrical charge and an atomic mass equal to the number of particles present. Surrounding the nucleus are 'shells' of electrons. These shells are also referred to as 'energy levels'. Electrons have a mass of just 1/1860th of an atomic mass unit so effectively, they do not contribute much to the mass of an atom. They have a charge of -1 and were the first of the subatomic particles to be discovered. An atom has the same number of electrons as protons so the electrical charges cancel out - atoms are neutral. An atom that is not neutral is not an atom, it is an ion.

The dangers and uses that we make of radioactive sources depends on their penetrating power and half-life. The half-life is a measure of how long it takes for the radiation level to fall by a half, more strongly radioactive materials have shorter half lives.

1.
What is background radiation due to?
Nuclear fallout
Rocks
Cosmic rays
All of the above
Cosmic rays account for most of the background radiation that we experience, however the other types can be major factors in specific areas
2.
What is an alpha particle?
A particle which has one neutron and one proton
A proton
A neutron
A particle which has two neutrons and two protons
It is the nucleus of a helium atom
3.
What is a beta particle?
A low energy electron
A high energy proton
A high energy electron
A low energy proton
Higher tier candidates may be asked to balance the atomic numbers and mass numbers in an equation showing what happens to an atom when it undergoes radioactive decay to produce an alpha or beta particle
4.
An electron
A proton
A neutron
It is the highest energy radiation of the electromagnetic spectrum
5.
Which type of radiation would be blocked by a thin sheet of paper?
Alpha
Beta
Gamma
None of the above
Alpha radiation also struggles to penetrate more than a few centimeters through the air
6.
Which type of radiation would be blocked by a thin sheet of aluminum - but not by paper?
Alpha
Beta
Gamma
They all get blocked
These fast-moving electrons are much smaller than alpha particles
7.
Which type of radiation would be blocked by several inches of lead - but not by a thin sheet of aluminum or paper?
Alpha
Beta
Gamma
Beta and Gamma
In nuclear reactors at nuclear power stations, gamma radiation is blocked from escaping by several meters of concrete
8.
What types of radiation can be deflected by electric and magnetic fields?
Alpha
Alpha and Beta
Alpha and Gamma
Beta and Gamma
Gamma radiation has no electrostatic charge
9.
What is the half-life of a radioactive isotope?
The time it takes to be deadly to humans
The number of isotopes in a sample
The average time it takes for the number of nuclei of the isotope in a sample to halve
The time it takes for the isotope in a sample to decrease by a quarter
This is why the count rate falls by half during one half life. It can be used to calculate how long it will take for the radiation from a particular sample of radioactive substance to drop to a safe level
10.
Which radiation is deflected more by electric and magnetic fields?
Alpha
Beta
Gamma
None are deflected
Alpha particles are deflected less, despite having a greater charge, due to having a much greater mass than beta particles. They are deflected in opposite directions as they have opposite charges
Author:  Martin Moore