Electromagnetic Induction Lecture Flashcards

Vocabulary terms and definitions covering the principles of electromagnetic induction, including relevant laws and electromagnetic devices.

Michael Faraday

Scientist (1791 - 1867) who proposed that magnetic fields could create electric fields and discovered that a changing magnetic field produces an electric current.

Induced emf

The voltage produced specifically by magnetic fields.

Induced current

The current produced from the voltage created by magnetic fields.

Electromagnetic induction

The phenomenon where an ammeter measures current in a circuit only when the magnetic field is changing, such as when a battery is switched on or off.

Magnetic flux ($\Phi$)

A measure of how much magnetic field passes through an area, defined as $\Phi = \int \mathbf{B} \cdot d\mathbf{A}$.

Weber ($Wb$)

The SI unit for magnetic flux, equivalent to $T \cdot m^2$.

Faraday’s Law of Induction

A law stating that the magnitude of the induced emf is proportional to the rate at which the magnetic flux changes through the circuit, expressed as $\mathcal{E} = -N \frac{d\Phi}{dt}$.

Lenz’s Law

The principle stating that an induced emf produces a current in a direction such that the magnetic field created by that current opposes the original change in flux.

Motional emf

An emf induced in a moving conductor, such as a rod dragged at a speed $v$ across a wire loop, defined by $\mathcal{E} = BLv$.

Dynamo

A machine that converts mechanical energy into electrical energy via the electromagnetic induction process.

AC generator

A device that produces alternating current by rotating a wheel with a coil of wires within a magnetic field using slip rings for continuous contact.

Split-ring commutator

A component used in DC generators instead of slip rings to ensure the output current flows in only one direction by flipping the connection when the current naturally reverses.

Eddy currents

Circulating currents produced in bulk pieces of metal when they move through a magnetic field with changing flux.

Magnetic damping

A force that opposes the motion of a metal object moving across a magnetic field, created by the movement of eddy currents.

Transformer

A device consisting of primary and secondary coils used to increase or decrease the voltage produced by an AC current.

Transformer equation

The relationship used to determine the voltage or current changes between primary ($p$) and secondary ($s$) coils: $\frac{V_s}{V_p} = \frac{N_s}{N_p} = \frac{I_p}{I_s}$.

Generalized Faraday’s Law

The mathematical expression showing that a changing magnetic field produces an electric field: $\oint \mathbf{E} \cdot d\mathbf{\ell} = -\frac{d\Phi}{dt}$.