17 consists two coils
called the primary and secondary coils windings, wound a
common core. 5.Basic scientific concepts electrotechnology
115
A current flowing coil wire solenoid establishes magnetic field
which very similar that bar magnet. supply such battery.
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. Winding the coil around a
soft iron core increases the flux density because the lines magnetic flux
concentrate the magnetic material.15
Magnetic fields around current carrying conductor.
. 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.
Electrical Transformers
A transformer electrical machine without moving parts, which used
to change the value alternating voltage. Figure 5.
● transformer such that shown Fig.
A transformer will only work alternating supply, will not normally
work from D.
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 5.16 shows the structure
and one application the solenoid.16
The solenoid and one practical application: the relay. This effect put practical use the electrical relay
as used motor starter alarm circuit. The iron core the transformer not solid but made
up very thin sheets called laminations, improve efficiency.C
