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Physics: Radioactivity And Particles: Units

Overview

Radioactivity is invisible, silent and completely beyond the reach of your senses. The only way to say anything useful about a radioactive source is to attach numbers to it, and numbers in physics are worthless without the right units.

This short lesson covers the handful of units you need for the whole radioactivity topic: the becquerel for activity, the centimetre for the distances and thicknesses used in absorption experiments, and the second, minute and hour for the times that appear in half-life questions. You will also practise the conversions that examiners build into calculation questions.

Objectives

  1. Use the following units: becquerel (Bq), centimetre (cm), hour (h), minute (min) and second (s)

Lesson Note

A sealed radioactive source sitting on a laboratory bench looks exactly like a small metal cylinder. Nothing about it looks, sounds or smells different from an ordinary piece of metal, yet inside it several thousand nuclei are breaking apart every second. The only handle physics gives you on that process is measurement, and every measurement in this topic is one of three things: how many decays happen per second, how far the radiation travels or how much material it passes through, and how long the source takes to weaken. Those three questions are exactly why the specification asks you to work in becquerels, centimetres, and seconds, minutes and hours.

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Lesson Evaluation

Congratulations on completing the lesson on Physics: Radioactivity And Particles: Units. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.

You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.

Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.

  1. The becquerel is the unit of: A) Half-life B) Activity C) Absorbed dose D) Count rate in a detector Answer: B
  2. An activity of 1 Bq means: A) One decay per minute B) One decay per hour C) One decay per second D) One thousand decays per second Answer: C
  3. A source has an activity of 2.5 kBq. In becquerels this is: A) 25 Bq B) 250 Bq C) 2500 Bq D) 25000 Bq Answer: C
  4. A detector records 600 counts in 5 minutes. The count rate in counts per second is: A) 2 counts per second B) 120 counts per second C) 12 counts per second D) 0.5 counts per second Answer: A
  5. An absorber is 6 mm thick. In centimetres this is: A) 0.06 cm B) 0.6 cm C) 6 cm D) 60 cm Answer: B

Available on the Green Bridge App

Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.

Full lesson notes with diagrams
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Study offline, anytime, anywhere
Available on Android, Windows, macOS, and Linux

Available on the Green Bridge App

Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.

Full lesson notes with diagrams
AI-powered learning assistant
Study offline, anytime, anywhere
Available on Android, Windows, macOS, and Linux

Practice Mock Questions

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