12. Some materials retain their magnetism,
while others lose it.11 dependent upon the rate change magnetic flux and the num-
ber turns the coil.12.
Magnetic hysteresis
There are many different types magnetic material and they all respond
differently being magnetized.Baisc Electrical Installation Work
206
FIGURE 10.
10.12
Magnetic hysteresis loops: (a) electromagnetic material and (b) permanent magnetic material. Some materials magnetize easily, and
some are difficult magnetize.
.
B
H
(a)
B
H
(b)
Magnetic saturation
Definition
Magnetic hysteresis loops describe
the way which different materials
respond being magnetized.
Magnetic hysteresis loops describe the way which different materials
respond being magnetized.
The core electromagnet required magnetize easily, and lose its
magnetism equally easily when switched off. Suitable materials will, there-
fore, display narrow hysteresis loop, shown loop (a) Fig.
Materials from which permanent magnets are made should display wide
hysteresis loop, shown loop (b) Fig.
Definition
A mutual inductance henry exists
between two coils when uniformly
varying current ampere per sec-
ond one coil produces emf 1
volt the other coil. 10.
When iron core subjected alternating magnetization, trans-
former, the energy loss occurs every cycle and constitutes continu-
ous power loss, and, therefore, for applications such transformers, a
material with narrow hysteresis loop required.12
and are called hysteresis loops. The result will look like the graphs shown Fig.
The emf induced coil such that shown the right-hand side Fig. 10.
Energy stored magnetic field
When open the switch inductive circuit such electric motor
or fluorescent light circuit the magnetic flux collapses and produces an
arc across the switch contacts. The arc produced the stored magnetic
energy being discharged across the switch contacts.
A mutual inductance henry exists between two coils when uniformly
varying current ampere per second one coil produces emf volt
in the other coil. 10
