Radioactivity
Visão Geral
Every second, invisible particles and waves pass through your body. Some come from the ground beneath your feet, others from space, and a few from the food you eat. Understanding radioactivity means understanding where this radiation comes from, what it can do, and how we harness it safely in medicine and industry.
This topic takes you inside the atom, through the three types of nuclear radiation, and into the mathematics of half-life. You will learn to write decay equations, compare the penetrating and ionising powers of alpha, beta and gamma radiation, and evaluate the real risks and benefits of working with radioactive materials.
Objetivos
- Describe the structure of an atom in terms of protons, neutrons and electrons and use symbols to describe particular nuclei
- Know the terms atomic (proton) number, mass (nucleon) number and isotope
- Know that alpha particles, beta particles, and gamma rays are ionising radiations emitted from unstable nuclei in a random process
- Describe the nature of alpha particles, beta particles and gamma rays, and recall that they may be distinguished in terms of penetrating power and ability to ionise
- Investigate the penetration powers of different types of radiation using either radioactive sources or simulations
- Describe the effects on the atomic and mass numbers of a nucleus of the emission of each of the four main types of radiation (alpha, beta, gamma and neutron radiation)
- Understand how to balance nuclear equations in terms of mass and charge
- Know that photographic film or a Geiger-Muller detector can detect ionising radiations
- Explain the sources of background (ionising) radiation from Earth and space
- Know that the activity of a radioactive source decreases over a period of time and is measured in becquerels
- Know the definition of the term 'half-life' and understand that it is different for different radioactive isotopes
- Use the concept of the half-life to carry out simple calculations on activity, including graphical methods
- Describe uses of radioactivity in industry and medicine
- Describe the difference between contamination and irradiation
- Describe the dangers of ionising radiations, including that radiation can cause mutations in living organisms, that radiation can damage cells and tissue, and the problems arising from the disposal of radioactive waste and how the associated risks can be reduced
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- Which type of radiation is the most ionising? A) Alpha B) Beta C) Gamma D) X-rays Answer: A
- What is the charge on a beta particle? A) +2 B) +1 C) 0 D) -1 Answer: D
- A radioactive source has a half-life of 4 hours. After 12 hours, what fraction of the original activity remains? A) 1/4 B) 1/8 C) 1/16 D) 1/3 Answer: B
- Which type of radiation is stopped by a few millimetres of aluminium? A) Alpha B) Beta C) Gamma D) Neutron Answer: B
- In beta decay, what happens inside the nucleus? A) A proton changes into a neutron B) A neutron changes into a proton and an electron C) Two protons and two neutrons are emitted D) Energy is released as an electromagnetic wave Answer: B
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Describe the structure and forces present within the nucleus
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Radiation Detection and Detectors
It is well known that ionizing radiation affects us but does not trigger nerve impulses. Newspapers carry stories about unsuspecting victims of radiation poisoning who fall ill with radiation sickness, such as burns and blood count changes, but who never felt the radiation directly. This makes the d
"College Physics: Radiation Detection and Detectors" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/college-physics/pages/31-2-radiation-detection-and-detectors. Access for free at https://openstax.org/books/college-physics/pages/1-introduction
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