Pratique du Shadowing: What is radiation? - Apprendre l'anglais à l'oral avec la vidéo
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Music What do smoke detectors,
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emergency lights, and nuclear power all have in common?
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Radiation.
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But what exactly is radiation?
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Thanks to high school science class, most of us have heard about radiation.
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But many of us may not know exactly what it is.
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I'm Julie, and I work for the Canadian Nuclear Safety Commission.
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Simply put, radiation is the release of energy in the form of moving waves or streams of particles.
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This energy can be low -level, like microwaves and cell phones, or high -level, like x -rays or cosmic rays from outer space.
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These are known as non -ionizing and ionizing radiation.
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But if we really want to understand radiation, we need to go inside the tiny world of the atom.
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Remember that high school science class?
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Atoms are the microscopic building blocks of all matter in the universe.
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Everything around us is made up of atoms, from the largest galaxies to our own bodies.
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The center of the atom is called the nucleus.
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That's where the word nuclear comes from.
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There is a tremendous amount of energy inside.
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The nucleus of an atom is made up of two particles, protons, which carry a positive charge, and neutrons, which have no charge.
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Outside the nucleus are electrons, which carry a negative charge the attraction of these negative electrons to the positive nucleus is what keeps the atom together.
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Now, every element in the periodic table has a specific number of protons and neutrons, but sometimes an atom will have too many or too few neutrons.
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When this happens, it becomes unstable or radioactive.
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An unstable atom is called a radioisotope.
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For example, two extra neutrons in a hydrogen atom creates the radioisotope tritium.
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That's the stuff that helps make exit lights glow in the dark.
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Radioactive atoms want to become stable again, so they release energy until they get back to a balanced state.
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This process is known as radioactive decay, and there are three main types, alpha, beta, and gamma.
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Alpha particles are heavy and travel small distances.
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Beta particles are lighter and travel further.
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And gamma radiation is actually a wave, and it travels the farthest of all.
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The time it takes for half of the radioactive atoms of a radioisotope to decay is called a half -life.
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Half -lives can range from a fraction of a second to billions of years.
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Let me give you an example of how half -lives come into play in nuclear medicine.
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Doctors inject patients with the radioisotope Technetium -99M, which emits gamma radiation.
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A gamma camera can then take pictures of the patient's insides to help with the diagnosis.
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The relatively short half -life of six hours for this radioisotope makes it ideal for these types types of tests.
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Let's pretend these jelly beans are the nuclei of TEC -99M.
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After one half -life, half the atoms still in the body remain unstable or radioactive.
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After two half -lives, one quarter of the atoms remain radioactive.
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After three half -lives, well, you get the idea.
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After 24 hours, almost all the radioactivity is gone, thanks to radioactive of decay and the body's natural, shall we say, processing?
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And that ends our science class on radiation.
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Congratulations, you passed.
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Now for the bonus question.
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Can you tell me who keeps an eye on the nuclear sector in Canada?
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That would be us, the Canadian Nuclear Safety Commission.
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We regulate the use of nuclear substances and materials and ensure that all nuclear materials are used for peaceful purposes.
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We also work to protect your health and safety, as well as that of the environment.
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The Canadian Nuclear Safety Commission.
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The answers you need from a source you can trust.
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Visit us at nuclearsafety .gc .ca on YouTube or Facebook.
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À propos de cette leçon
Vous vous entraînez en anglais avec "What is radiation?" en utilisant la technique du Shadowing.
Qu'est-ce que la technique du Shadowing ?
Le Shadowing est une technique d'apprentissage des langues fondée sur la science, développée à l'origine pour la formation des interprètes professionnels. Le principe est simple mais puissant : vous écoutez de l'anglais natif et le répétez immédiatement à voix haute — comme une ombre suivant le locuteur avec un décalage de 1 à 2 secondes. Les recherches montrent une amélioration significative de la précision de la prononciation, de l'intonation, du rythme, des liaisons, de la compréhension orale et de la fluidité.