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Electromagnetism - Coggle Diagram
Electromagnetism
magnetism
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how close together the magnetic lines are to one another indicates the strength of the magnetic field
no matter the object's shape or size, the number of magnetic lines entering the object will always be exactly equal to the number of magnetic lines leaving the object
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If we increase the amount of charge passing through the loop, the strength of the magnetic field increases.
negative particles flowing though a loop, create a magnetic field in the opposite direction
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in the case of magnetic fields, particles feel a force in a direction that is 90 degrees to the magnetic field
and 90 degrees to the direction of motion
particles with the same charge moving in the same direction result in a magnetic force attracting them together
particles with the same charge moving in opposite directions result in a magnetic force pushing them apart
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a magnetic is a meterial which many of its negatively charged particles are spining in the same direction
every rotating charged particle is a miniature magnet and every magnet can be thought of as a rotating loop of charged particles
opposite poles attract one another, similar repel one another.
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coils and magnets create powerful magnetic fields, but they are electrically neutral
this is because magnets and coils have positive particles in equal quantity to the negative particles
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materials affected by a magnet, create a magnetic field in the same direction as the external field, thus making the total magnetic field stronger
just as magnetic field arrows pointed in opposite directions cancel each other out, charges passing through the loop in opposite directions also cancel each other out
if the loop is pointed in a different direction than the magnetic field, each arrow can be thought of as the combination of an arrow pointed 90 degrees to the loop's path and an arrow parallel to the loop's path, only the parallel arrow gets counted for the sum of arrow lengths
a rotating magnet creates a rotating magnetic field (AC current also creates a rotating magnetic field)
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electricism
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the electric field is strongest near the charged particle, because this is where the greatest number of electric lines are close together
charges outside the object bend the electric lines but do not change the number of electric lines that leave the object
the only way to increase the number of electric lines leaving the object is by increasing the amount of charge in the object
since the amount of charge in the object is doubled, there are now twice as many electric lines leaving the object, therefore the electric field is twice as strong
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particles with the same charge repel one another, particles with opposite charge attract one another.
this is because positive particles cause electric fields to point away from the particle, and negative particles cause electric fields to point towards the particle
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In the case of electric fields, particles feel a force parallel to the diretion of the electric field
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Maxwell's fourth law
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the sum of electric arrow lengths around a loop is determined by the rate of which the magnetic field through the loop is changing with time
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this is true regardless of the loop's shape or size, or regardless of how you twist or bend the loop
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Maxwell's third law
the strength of a magnetic field around a loop depends on the amount of charge passing through the loop each second
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remains true regardless of the loop's shape or size, we can even bend and twist the loop
if the number of electric field lines passing thorugh a loop is changing with time, then this will also create a magnetic field around the loop
the sum of magnetic field arrow lengths is determined by the amount of charge passing through the loop each second, plus the rate at which the electric field through the loop is changing with time
electromagnetism
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in the case of electric fields, the strength of a force on a particle is proportional to the amount charge in the particle multiplied by the strength of the electric field
in the case of magnetic fields, the strength of the force on a particle is proportional to the amount of charge in the particle multplied by the area of motion cross field vector
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if we change the direction of motion, the rectangle becomes a parallelogram, and the area changes accordingly
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Maxwell's first law
the number of electric field lines leaving the object is only determined by the amount of charge in the object
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as long as the amount of charge in the object does not change, the number of electric field lines leaving the object will stay the same
transformer
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when one changes direction (the magnetic field changes) and thus an electric field (opposite direction of change) will make the other coil go in the opposite direction
remember that the secondary magnetic field is created to cancel the change of the primary magnetic field, and also remember that the strength of a magnetic field through a loop is amount of charge passing through per second
So if the amount of charge passing through the primary loop is 1A (primary coil has 1 winding), then the amount of charge passing through the secondary loop is also 1A, but since it has 2 windings, the circuit current is 1/2=0.5 A.
Maxwell's second law
the sum of number of magnetic lines leaving the object and the number of magnetic lines entering the object is always zero
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