P4.5 - electromagnetic effects Flashcards
what is electromagnetic induction?
phenomenon by which an electric current is induced in a closed coil or a conductor when there is a relative motion between the coil and the magnetic fields
3 factors affecting amount of induced current?
-strength of magnet(ic field)
-speed of movement
-length of conductor / coil (longer = more = increased size of induced emf)
4 parts of AC generator (dynamo) ? features?
MAGNETS
-N&S are present
-provides electromagnetic field
ARMATURE COIL
-coil of a conductor
-rotates between 2 magnets
-used to cut magnetic field lines
SLIP RINGS
-2 are present
-provides electrical contact between armature coil and brushes
BRUSHES
-2 are present
-connected to slip rings
-provides current to the load
what is the principle working of AC generator?
AC generator works on the principle of electromagnetic induction in which magnetic field lines are cut by coil to produce current in the field
a ____ carrying wire always has __________ _______ associated with it
-current
-magnetic
-field
3 features of concentric circles?
-have the same centre
-flipping the cell terminals changes the direction of current in circles
-further from axis, ring is further away
what is a solenoid?
long insulated current carrying coil
what do solenoids act as?
bar magnet (field is N –> S)
how does strength of solenoid increase?
by introducing of iron substance in its axis
how is the field in the axis of the solenoid?
strong (dense and close together) and uniform (not changing)
how is the turning effect increased? [3]
-increasing number of turns on the coil
-increasing current
-increasing the strength of the magnetic field
when is emf induced?
when there is relative movement between conductor and magnetic field
