Magnetic fields
- Created by: April_Higgin
- Created on: 02-01-15 22:20
A magnetic field is a region in which a particle with magnetic properties experiences a force, and in which a moving particle experiences a force.
Magnetic flux is the flow of field lines. (units Wb)
There are two types of magnets: Permanent, and electro.
Permanent magnets:
The fields lines ALWAYS go from north to south.
The arrows represent the direction of the force that a free north pole would experience.
The closer the lines are, the stronger the magnetic field.
Electromagnets:
The cross in the centre of the wire shows the wire is going away from us.
Direction of field: into page- clockwise, out of page- anticlockwise
Where to magnets coincide and cancel each other out, it is called a neutral point.
Magnetic Field Strength (B)
Aka: mangetic flux density. (units T)
Flux density is dependent on the amount of flux and the angle of the area (often a coil) to the field.
1 T = 1 Wb/m²
1 T is VERY BIG. a strong permanent magnet is about 0.1 T
A magnetic field has a strength of 1T if a wire of length 1 metre experiences a force of 1N when a current of 1A flows in the wire.
Force on a wire generating a current = BIL
The direction of the force is given by Fleming's left hand rule:
A couple on a coil.
Torque (C) on the coil = Fa sinθ = BNIba sin θ or:
Torque (C) on the coil = BANI sinθ
Treat this as a moments question.
Moving Charges
Diriving the equation for moving charges.
F = BIL I =…
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