The advantage the electromagnet
when compared with the permanent magnet that the magnetism the
electromagnet can switched and off functional switch control-
ling the coil current.
Pivot
Movable
armature
Air gap
Movement
of arm
Simple relay
Lines magnetic flux
around solenoid with
a soft iron core
Lines magnetic flux
around solenoid with
no core
Lines magnetic flux Spring
Solenoid
FIGURE 5.Basic scientific concepts electrotechnology
115
A current flowing coil wire solenoid establishes magnetic field
which very similar that bar magnet.
Conductor
The dot indicates
current flowing
towards our viewing
position
(a) The cross indicates
current flowing away
from our viewing
position
(b)
Lines of
magnetic flux
FIGURE 5. supply such battery. This effect put practical use the electrical relay
as used motor starter alarm circuit.
● transformer such that shown Fig.C. 5. The iron core the transformer not solid but made
up very thin sheets called laminations, improve efficiency.16 shows the structure
and one application the solenoid.
A transformer will only work alternating supply, will not normally
work from D.16
The solenoid and one practical application: the relay.
. Figure 5.15
Magnetic fields around current carrying conductor. Winding the coil around a
soft iron core increases the flux density because the lines magnetic flux
concentrate the magnetic material.
Electrical Transformers
A transformer electrical machine without moving parts, which used
to change the value alternating voltage.17 consists two coils
called the primary and secondary coils windings, wound a
common core
