Magnetic Fields Flashcards
(10 cards)
strength of a magnetic field
The strength of the magnetic field in the centre of coils or solenoids can be increased by:
Adding more loops or turns to the coil (increasing N).
Decreasing the cross-sectional area of the coil (decreasing A).
Increasing the current flowing through the coil (increasing I).
for path of an electron in a magnetic field…
Reverse the direction of the current
the current is the opposite direction of the motion of an electron,
pos -> negative
define magnetic flux and magnetic flux linkage
magnetic flux= value which describes the magnetic field/field lines passing through an area. It is the product of magnetic flux density and the perpendicular area it passes through
magnetic flux linkage = The magnetic flux multiplied by the number of turns, N, of the coil.
what is lenz’s law
An induced current is always in a direction so as to oppose the
change that caused it.
cyclotron
2 semicircular ‘Dees ‘ in the middle
each are electrodes, oppositely charged= electric field , this initially accelerates the particles
there is a magnetic field perpendicular to the Dees, this provides circular motion to the particle,
as their speed increases, so does their orbital radius, at some point of getting to a certain orbital radius, it escapes the cyclotron tangential to one of the Dees
why does the output from a output-voltage waveform alternate
purpose of the core in a transformer
increases linkage of magnetic flux from primary to secondary coil
compared to just air between the 2 coils
Purpose of the secondary coil
the secondary coil will have varying magnetic flux through it,
causing an induced EMF produced
Size of this induced EMF depends on the ratio of turns between the 2 coils
why may a transformers core be laminated
Laminated core = core constructed of thin metal sheets separated by a material
More efficient since it increases the resistance- meaning lower Eddy Current
Lamination of metals uses High resistivity metals
