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Flashcards in Electromagnetism Pure Def ! Deck (15)
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What is a magnetic field?

Is the region around a permanent magnet or a moving charge in which another body with magnetic properties will feel a force.


What is a solenoid?

A long coil of current-carrying wire


Define magnetic flux

(O, w/ line in middle) Is the product of magnetic flux density, B, and the area, A, at right angles to the flux. Given by OI = BA CosO ( where O is the angle between the field lines and the normal to the surface). Measured in Webers (Wb).


Define magnetic flux density

B, is a measure of the strength of the magnetic field and defined by the equation for the force on a current-carrying conductor in a magnetic field, F= BIL SinO. The units are, T, Tesla, or, Wbm^-2, Webers per square meter


One Weber

(Wb) is the magnetic flux when a magnetic field of magnetic flux density one Tesla passes at right angles through an area of one square metre.


Fleming’s left-hand rule

Thumb - Force (F)
First finger - Field (B)
Second finger - Current (I)
Shows the direction of the force on a conductor carrying a current in a magnetic field.


Electromagnetic induction

Is the process of inducing an e.m.f in a conductor when there is a magnetic flux linkage across the conductor


Induced e.m.f.

Is the e.m.f. produced by electromagnetic induction


Magnetic flux linkage

For a coil equals the product of the magnetic flux through the coil and the number of turns on the coil. From magnetic flux linkage = NOI, the units are Weber turns.


Fleming’s right-hand rule

ThuMb - Direction of Motion of the wire relative to the field
First Finger - Direction of the Field
SeCond finger - Direction of the induced Current


Faraday’s law of electromagnetic induction

States that the magnitude of the induced e.m.f. is equal to the rate of change of flux linkage


Lenz’s law

States that the direction of any induced e.m.f. or induced current is in a direction that opposes the flux change that causes it



Device used to generate electricity, in which the work done to turn the coil within the magnetic field is transferred to electrical energy. The rotation of the coil within a magnetic field produces a constantly changing flux linkage through the coil. This in turn produces a constantly changing induced e.m.f. in the coil.


Alternating current (a.c)

is electrical current that reverses its direction with a constant frequency.



A device that can either increase or decrease the size of the alternating voltage with little loss of power