Year 13 - Magnetic Effects Flashcards
1 Tesla
The (strength) of the magnetic field / flux density that produces a force of 1 newton in a wire of length 1m with 1 ampere (flowing perpendicular to the field) e.g. F=BIL.
Alternating Current
An A.C.changesdirection (twice every cycle).
Cyclotron
A particle accelerator made up of two D shaped electrodes positioned opposite each other. The electric field changes direction each time a particle moves from one electrode to the other, causing the particle to accelerate.
Eddy Current
Emf induced in core of Transformer due to changing magnetic field. Current flows in the transformer core as it is made from conducting material.
Electromagnetic Induction
When an e.m.f. is induced in a wire/conductor when it is moved relative to a magnetic field. Perpendicular motion induces the greatest e.m.f.
Faraday’s Law
The induced e.m.f. is directly proportional to the rate of change of magnetic flux linkage.
Induced e.m.f.
The induction/generation of anelectro-motive forcee.m.f. by way of cutting a magnetic field with an electric conductor.
Lenz’s Law
The direction of the induced e.m.f. (when there is a change of flux linkage) is such that it will (try) to oppose the change (of flux) that is producing it.
Magnetic Field
A region surrounding a magnet or current-carrying wire that will exert a force on any other magnet/magnetic material or current-carrying wire placed within it.
Magnetic Flux
Magnetic flux through a plane surfaceis the product of the magnetic flux density normal to the surface BN and the area A of the surface.
Magnetic Flux Density
A measurement of the total magnetic flux per unit area.
Magnetic Flux Linkage
The product of the number of turns N of the coil and the magnetic flux linking each turn, in Weber’s (Wb).
Motor Effect
When a current-carrying wire is placed perpendicular within a magnetic field and experiences a force perpendicular to both the wire and the field lines. (Flemings Left-hand Rule).
Step-Down Transformer
A device made of two insulated wires coiled around an iron core in which the output voltage is smaller than the input voltage, due to the secondary coil having fewer turns than the primary coil.
Step-Up Transformer
A device made of two insulated wires coiled around an iron core in which the output voltage is greater than the input voltage, due to the secondary coil having more turns than the primary coil.
The Weber
The magnetic flux through a surface if a magnetic field of flux density 1 T exists perpendicularly to an area of 1 m2.
Transformer
A device that can change the potential difference of an alternating current. A transformer is made from two coils of wire, a primary coil and a secondary coil. The coils are wound around an iron core.
Transformer Core
Provides greater linkage/increases linkage of magnetic flux/field.
Transformer Core Lamination
The laminations are made from insulator/high resistivity material which reduces/limits (eddy) currents or charge flowing in the core. Thin laminations of iron are used so smaller emf’s are induced in the core.
