Electromagnetism
Overview
When electric current flows through a wire, it creates a magnetic field around it. This simple fact is the basis of motors, loudspeakers and countless other devices that convert electrical energy into motion.
In this lesson you will learn how current-carrying conductors produce magnetic fields, why a force acts on a current in a magnetic field (the motor effect), how to use the left-hand rule, and what factors change the force on the conductor.
Objectives
- Know that an electric current in a conductor produces a magnetic field around it
- Understand why a force is exerted on a current-carrying wire in a magnetic field, and how this effect is applied in simple d.c. electric motors and loudspeakers
- Use the left-hand rule to predict the direction of the resulting force when a wire carries a current perpendicular to a magnetic field
- Describe how the force on a current-carrying conductor in a magnetic field changes with the magnitude and direction of the field and current
Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Electromagnetism. 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.
- The motor effect is the force on: A) A magnet near iron B) A current-carrying wire in a magnetic field C) A stationary wire D) An insulator in a field Answer: B
- Fleming's left-hand rule: the thumb represents: A) Field B) Current C) Motion/force D) Resistance Answer: C
- In a d.c. motor, the commutator: A) Increases voltage B) Reverses current every half turn C) Increases resistance D) Produces a.c. Answer: B
- The force on a current-carrying wire increases when: A) Current decreases B) Field weakens C) Current increases D) Wire is shortened Answer: C
- A loudspeaker converts: A) Sound to electrical energy B) Electrical to sound energy C) Heat to sound D) Kinetic to electrical 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.
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.
Practice Mock Questions
Want to practice mock questions on Electromagnetism? Download the Green Bridge CBT app to access mock questions and full practice assessments for this topic.
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