Magnetic Fields Flashcards
A magnetic field is
A region where a forced is exerted on a magnetic material
Field lines go from
North to south
Closer the field lines
stronger the field
A magnetic field is induced around a wire when
a current flows in the wire
Fields lines around the wire are
concentric, centred n the wire
Direction of magnetic field can be worked out by
right hand thumb rule
Doughnut shaped field=
loop wire into coil
Bar magnet shaped field=
lots of coils (=solenoid)
conventional current and electron flow
are in the opposite directions to each other
For no force to act
the current is parallel to the flux lines
The direction of the force is alway perpendicular to both
the current and the magnetic field
Flemings Left hand rule
Thumb=Motion
First finger= field
Second finger= current
Current flows from
positive to negative
Size of the force on a current carrying wire perp to magnetic field is proportional to
Current I
Length of wire l
Strength of m. field B
F=BIl
Magnetic field strength is defined as
the force on one metre of wire carrying a current of one amp at right angles to the magnetic field
