A coil without core by a direct voltage supply through the flow meter. Bring a small iron, eg clip, notice what happened. Then fill the coil with an iron core, bring the little iron sebua, observe what happened.
Image 1,116 coils with and without iron core
Interesting iron core iron clip with stronger than without an iron core, shown in Figure 1.116. Tersearahkan iron molecules by a magnetic field generated by the coil. Sehinngga iron nuclei have magnetic properties. The strength of the magnetic coil current rises with the increase, but at a certain amount of current the magnetic force does not rise again (saturated). Iron magnetic conditions on the same field strength in a few different materials. In 1117 the picture depicted the condition, which is described density field (B) of the iron core of a coil in dependence on the field strength (H).
Figure 1117 Curves Magnetism
Comparison with the magnetic flux density of magnetic field strength is called permeability. Permeability is the product of a constant magnetic field with relative permeability.
μ = permeability
B = magnetic flux density
H = magnetic field strength
μo = constant magnetic field
μr = relative permeability
Relative permeability is, how many times greater flux density of a coil between the core and without core. The relative permeability of air is 1. The relative permeability of the ferromagnetic material amount of about several thousand, see Table 1.11.
Table 1.11 The relative permeability μr max
When the flow of a coil around an iron core flux density is increased then it will go up. Molecular magnets at the core to be drawn, strong magnetic field flux density is going up and will go up anyway. Until the saturation level. When the field strength is lowered, the flux density will also go down, but not as fast as the decline in field strength. The field strength is lowered by minus (reverse flow) then the flux density will increase until it reaches the level of saturation negative negative (opposite direction).
If then the field strength is lowered, it happened the same as on the positive side. Until a strong graphic image field flux density function as shown below called histeristis meshes. This is shown in Figure 1118.
1118 Image hysteresis curve Meshes
From the snares of hysteresis can be seen that in the end on the fiber will be left behind remanence. If desired loss of remanence then do as was done earlier followed repeated with field strength gradually diminished until robust terrain is zero (Figure 1.119).
Image 1119 demagnetization
This principle is applied to the elimination of magnetic tape, on cassette tape and reel and the like.