What is the relationship between electricity and magnetism?
In this unit students investigate how electrical fields and magnetic fields interact to produce motion (electrical motors) or electricity (generators). First they explore the defining characteristics of magnets and their interactions with other magnets and magnetic materials. Then students do the same for electric charges and their interactions with various neutrally charged materials. This then allows them to compare and contrast magnetic interactions and electric charge interactions. Next students explore how the magnetic compass is used to detect current in a wire and to also note its directionality. This then leads to exploring the interactions between electrical fields and magnetic fields that can produce mechanical energy (motion) in a motor or produce electrical current and energy in a generator. This unit concludes with students building a simple electric motor and/or generator that is used to demonstrate these concepts. This provides a way to explain how these devices work using the basic interaction concepts learned in this unit.
STANDARD P3: FORCES AND MOTION Students identify interactions between objects either as being by direct contact (e.g., pushes or pulls, friction) or at a distance (e.g., gravity, electromagnetism), and to use forces to describe interactions between objects. They recognize that non-zero net forces always cause changes in motion (Newton’s fi rst law). These changes can be changes in speed, direction, or both. Students use Newton’s second law to summarize relationships among and solve problems involving net forces, masses, and changes in motion (using standard metric units). They explain that whenever one object exerts a force on another, a force equal in magnitude and opposite in direction is exerted back on it (Newton’s third law).
P3.1 Basic Forces in Nature
P3.1A Identify the force(s) acting between objects in “direct contact” or at a distance.
P3.1c Provide examples that illustrate the importance of the electric force in everyday life.
P3.1d Identify the basic forces in everyday interactions.
P3.8x Electromagnetic Force
P3.8b Explain how the interaction of electric and magnetic forces is the basis for electric motors, generators, and the production of electromagnetic waves.
P4.2 Energy Transformation
P4.2A Account for and represent energy transfer and transformation in complex processes (interactions).
P4.2B Name devices that transform specific types of energy into other types (e.g., a device that transforms electricity into motion).
P4.10 Current Electricity — Circuits
P4.10A Describe the energy transformations when electrical energy is produced and transferred to homes and businesses.
P4.10B Identify common household devices that transform electrical energy to other forms of energy, and describe the type of energy transformation.
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- How are magnetic interactions and electric charge interactions similar and different?
- How can a magnetic field be used to move electric charges?
- How can electric charges be used to produce magnetism?
- What are the similarities and differences between motors and generators?
electrical current (AC and DC)
magnetic and electric forces
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