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Questions and Answers
Which of the following best describes electromagnetic induction?
Which of the following best describes electromagnetic induction?
- The creation of an electric field due to a static magnetic field.
- The production of an electromotive force across an electrical conductor in a changing magnetic field. (correct)
- The generation of an electromotive force across a conductor exposed to a changing electric field.
- The flow of current through a conductor with constant resistance.
Michael Faraday's initial experiment involved wrapping two wires around an iron ring. What key observation led him to the discovery of electromagnetic induction?
Michael Faraday's initial experiment involved wrapping two wires around an iron ring. What key observation led him to the discovery of electromagnetic induction?
- A constant voltage was induced in the second wire, proportional to the current in the first.
- The iron ring became permanently magnetized, inducing a continuous current.
- A continuous, unchanging current flowed as long as the battery was connected.
- A transient current appeared in the second wire only when the current in the first wire was connected or disconnected. (correct)
Why were Faraday's initial ideas regarding electromagnetic induction not widely accepted by scientists at the time?
Why were Faraday's initial ideas regarding electromagnetic induction not widely accepted by scientists at the time?
- His explanations relied on abstract concepts and lacked mathematical formulation. (correct)
- Scientists already had a comprehensive understanding of electromagnetism.
- His theories contradicted established laws of thermodynamics.
- His experiments were poorly documented and difficult to reproduce.
Which of the following is a practical application of electromagnetic induction?
Which of the following is a practical application of electromagnetic induction?
How did James Clerk Maxwell contribute to the understanding of electromagnetic induction?
How did James Clerk Maxwell contribute to the understanding of electromagnetic induction?
What observation did Faraday make when he quickly moved a bar magnet in and out of a coil of wires?
What observation did Faraday make when he quickly moved a bar magnet in and out of a coil of wires?
Oliver Heaviside's version of Faraday's law, as part of Maxwell's equations, differs from Faraday's original formulation in that it:
Oliver Heaviside's version of Faraday's law, as part of Maxwell's equations, differs from Faraday's original formulation in that it:
Which of the following scenarios would NOT result in electromagnetic induction?
Which of the following scenarios would NOT result in electromagnetic induction?
Flashcards
Electromagnetic Induction
Electromagnetic Induction
Production of an electromotive force (EMF) across a conductor due to a changing magnetic field.
Michael Faraday
Michael Faraday
He discovered electromagnetic induction in 1831.
Lenz's Law
Lenz's Law
Describes the direction of the induced magnetic field.
Maxwell-Faraday Equation
Maxwell-Faraday Equation
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Inductors
Inductors
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Transformers
Transformers
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James Clerk Maxwell
James Clerk Maxwell
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Faraday's Disk
Faraday's Disk
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Study Notes
- Electromagnetic or magnetic induction involves producing an electromotive force (EMF) across an electrical conductor when exposed to a changing magnetic field.
- Michael Faraday discovered induction in 1831.
- James Clerk Maxwell mathematically described induction as Faraday's Law of Induction.
- Lenz's Law describes the direction of the induced field.
- Faraday's Law was generalized into the Maxwell-Faraday equation.
- The Maxwell-Faraday equation is one of the four Maxwell equations in the theory of electromagnetism.
- Electromagnetic induction applications include electrical components like inductors and transformers, and devices like electric motors and generators.
Faraday's Experiment
- August 29, 1831: Faraday's first demonstration involved wrapping two wires around opposite sides of an iron ring or "torus".
- When current started to flow in one wire, Faraday expected a wave to travel through the ring and cause an electrical effect on the opposite side.
- Connecting one wire to a galvanometer, Faraday observed a transient current ("wave of electricity") when connecting/disconnecting the other wire to a battery.
- Induction occurred due to the magnetic flux change when the battery was connected and disconnected.
- Faraday found other electromagnetic induction manifestations within two months.
- Transient currents were observed when sliding a bar magnet in/out of a wire coil.
- Steady (DC) current was generated by rotating a copper disk near a bar magnet with a sliding electrical lead ("Faraday's disk").
Faraday's Explanation
- Faraday explained electromagnetic induction using "lines of force".
- Scientists widely rejected Faraday's theoretical ideas due to the lack of mathematical formulation.
- James Clerk Maxwell used Faraday's ideas as the basis of his quantitative electromagnetic theory.
- In Maxwell's model, the time-varying aspect of electromagnetic induction is expressed as a differential equation.
- Oliver Heaviside referred to the differential equation as Faraday's Law.
- Heaviside's version (Maxwell-Faraday equation) is recognized today in Maxwell's equations.
Lenz's Law
- In 1834, Heinrich Lenz formulated Lenz's Law to describe the "flux through the circuit".
- Lenz's Law defines the direction of induced EMF and current resulting from electromagnetic induction.
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