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Electro-Magnetism
© David Hoult 2009
Magnetic Field Shapes
© David Hoult 2009
Magnetic fields are represented by lines called lines of magnetic force or lines of magnetic flux
© David Hoult 2009
Magnetic fields are represented by lines called lines of magnetic force or lines of magnetic flux
These lines show the direction of the force which would act on a free north magnetic pole placed in the field
© David Hoult 2009
Magnetic fields are represented by lines called lines of magnetic force or lines of magnetic flux
These lines show the direction of the force which would act on a free north magnetic pole placed in the field
However, since free north magnetic poles don’t exist... think of the lines as showing which way a very small compass would point if placed in the field
© David Hoult 2009
Magnetic fields are represented by lines called lines of magnetic force or lines of magnetic flux
These lines show the direction of the force which would act on a free north magnetic pole placed in the field
However, since free north magnetic poles don’t exist... think of the lines as showing which way a very small compass would point if placed n the field
The “density” of lines on a diagram indicates the strength of the magnetic field
© David Hoult 2009
Field due to a straight current-carrying conductor
© David Hoult 2009
Field due to a straight current-carrying conductor
© David Hoult 2009
It is found that a compass always points perpendicular to the conductor so we conclude that the lines form circles (or cylinders) round the conductor
© David Hoult 2009
To remember the sense of the magnetic field, think about
© David Hoult 2009
To remember the sense of the magnetic field, think about opening a bottle of wine.
© David Hoult 2009
To remember the sense of the magnetic field, think about opening a bottle of wine.
© David Hoult 2009
To remember the sense of the magnetic field, think about opening a bottle of wine.
demo... © David Hoult 2009
To remember the sense of the magnetic field, think about opening a bottle of wine.
© David Hoult 2009
Field due to a short current-carrying coil of wire
© David Hoult 2009
Field due to a short current-carrying coil of wire
© David Hoult 2009
Field due to a short current-carrying coil of wire
© David Hoult 2009
Field due to a long current-carrying coil of wire (also called a solenoid)
© David Hoult 2009
Field due to a long current-carrying coil of wire (also called a solenoid)
© David Hoult 2009
Field due to a long current-carrying coil of wire (also called a solenoid)
© David Hoult 2009
This field is similar to that of a bar magnet
© David Hoult 2009
This field is similar to that of a bar magnet
© David Hoult 2009
This field is similar to that of a bar magnet
© David Hoult 2009
This field is similar to that of a bar magnet
© David Hoult 2009
This field is similar to that of a bar magnet
© David Hoult 2009
Current into plane of diagram
© David Hoult 2009
Current into plane of diagram
Current out of plane of diagram
© David Hoult 2009
Fields due to two parallel current-carrying conductors
© David Hoult 2009
Fields due to two parallel current-carrying conductors Currents flowing in the same sense
© David Hoult 2009
Fields due to two parallel current-carrying conductors Currents flowing in the same sense
© David Hoult 2009
Fields due to two parallel current-carrying conductors Currents flowing in the same sense
© David Hoult 2009
Fields due to two parallel current-carrying conductors Currents flowing in the same sense
© David Hoult 2009
Fields due to two parallel current-carrying conductors Currents flowing in the same sense
© David Hoult 2009
Fields due to two parallel current-carrying conductors Currents flowing in the same sense
The two conductors attract each other© David Hoult 2009
Currents flowing in opposite sense
© David Hoult 2009
Close to the conductors the field is very nearly circular
© David Hoult 2009
© David Hoult 2009
The field is similar in shape to the field of a
© David Hoult 2009
The field is similar in shape to the field of a short coil
© David Hoult 2009
The field is similar in shape to the field of a short coil
The two conductors repel each other
© David Hoult 2009
