Electromagnetic Effects
Overzicht
Move a magnet near a coil of wire and a voltage springs up out of nowhere; send a current through a wire and it becomes wrapped in a magnetic field; place that wire in another magnet's field and it is pushed sideways. Electricity and magnetism are two sides of one coin, and this link runs every generator, motor, relay and loudspeaker.
In this topic you will learn how a changing magnetic field induces an e.m.f., what affects its size and direction, the magnetic field patterns around wires and solenoids, and how a simple a.c. generator works. You will also relate the directions of force, field and current, and see the magnetic effect of a current applied in relays and loudspeakers.
Doelstellingen
- Know that a conductor moving across a magnetic field or a changing magnetic field linking with a conductor can induce an e.m.f. in the conductor
- Describe an experiment to demonstrate electromagnetic induction
- State the factors affecting the magnitude of an induced e.m.f.
- Describe the pattern and direction of the magnetic field due to currents in straight wires and in solenoids
- Describe an experiment to identify the pattern of the magnetic field (including direction) due to currents in straight wires and in solenoids
- Describe how the magnetic effect of a current is used in relays and loudspeakers and give examples of their application
- [Supplement] Know that the direction of an induced e.m.f. opposes the change causing it
- [Supplement] State and use the relative directions of force, field and induced current
- [Supplement] Describe a simple form of a.c. generator (rotating coil or rotating magnet) and the use of slip rings and brushes where needed
- [Supplement] Sketch and interpret graphs of e.m.f. against time for simple a.c. generators and relate the position of the generator coil to the peaks, troughs and zeros of the e.m.f.
- [Supplement] State the qualitative variation of the strength of the magnetic field around straight wires and solenoids
- [Supplement] Describe the effect on the magnetic field around straight wires and solenoids of changing the magnitude and direction of the current
Audioles
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Mindmap
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Lesevaluatie
Gefeliciteerd met het voltooien van de les op Electromagnetic Effects. Nu je de sleutelconcepten en ideeën, het is tijd om uw kennis op de proef te stellen. Deze sectie biedt een verscheidenheid aan oefeningen vragen die bedoeld zijn om uw begrip te vergroten en u te helpen uw begrip van de stof te peilen.
Je zult een mix van vraagtypen tegenkomen, waaronder meerkeuzevragen, korte antwoordvragen en essayvragen. Elke vraag is zorgvuldig samengesteld om verschillende aspecten van je kennis en kritisch denkvermogen te beoordelen.
Gebruik dit evaluatiegedeelte als een kans om je begrip van het onderwerp te versterken en om gebieden te identificeren waar je mogelijk extra studie nodig hebt. Laat je niet ontmoedigen door eventuele uitdagingen die je tegenkomt; beschouw ze in plaats daarvan als kansen voor groei en verbetering.
- An e.m.f. is induced in a coil when: A. a magnet rests inside it B. the magnetic field through it changes C. it is painted black D. it is at a high temperature Answer: B
- Which change does NOT increase the e.m.f. induced in a coil? A. moving the magnet faster B. using more turns C. using a stronger magnet D. holding the magnet still Answer: D
- The magnetic field around a long straight current-carrying wire is: A. straight lines along the wire B. concentric circles around the wire C. a uniform field D. zero Answer: B
- In a simple a.c. generator the induced e.m.f. is greatest when the coil is: A. vertical B. horizontal C. at rest D. removed Answer: B
- The force on a current-carrying wire in a magnetic field is found using: A. the right-hand grip rule B. Fleming's right-hand rule C. Fleming's left-hand rule D. Ohm's law Answer: C
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Aanbevolen Boeken
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Leerboekparagraaf
Electromagnetic Induction
Explain how a changing magnetic field produces a current in a wire
"Physics: Electromagnetic Induction" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/physics/pages/20-3-electromagnetic-induction. Access for free at https://openstax.org/books/physics/pages/1-introduction
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Leerboekparagraaf
Magnetic Fields, Field Lines, and Force
Summarize properties of magnets and describe how some nonmagnetic materials can become magnetized
"Physics: Magnetic Fields, Field Lines, and Force" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/physics/pages/20-1-magnetic-fields-field-lines-and-force. Access for free at https://openstax.org/books/physics/pages/1-introduction
Gepubliceerd door andere organisaties onder open licenties, vermeld zoals zij vragen. Links openen hun websites.
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