Magnetic field is not perceived by sense organs of the person. For its detection it is possible to use various mechanical and electric devices and devices. Some of them also allow to define polarity of the field and a form of its power lines.
It is required to you
- - paper clip or nail;
- - magnet;
- - vessel with oil and particles of oxide of iron;
- - Hall's sensor;
- - coil;
- - power supply;
- - galvanometer.
Instruction
1. The simplest device for detection of magnetic field is any small steel subject: nail, paper clip, and so forth. The exception is made by the devices manufactured of non-magnetic grades of stainless steel. In the presence of the field such subject will be attracted to its source. Consider that it is impossible to define polarity of the field by means of such adaptation. It is connected with the fact that magnetosoft ferromagnetic materials in the presence of the field are remagnetized in opposite polarity. For this reason they are attracted to any poles of magnets.
2. If it is required to define not only existence of magnetic field, but also its polarity, use a magnet. Its force has to be approximately the same as force of a source of the required field. At non-compliance with this condition either this source, or a magnet will be remagnetized with opposite polarity. A lack of a magnet is its ability to be attracted also to those ferromagnetic objects which are not magnetized. Therefore at first you bring to an estimated source of the field not magnetized steel subject, and only then a magnet. When determining polarity of the field consider the fact that identical poles makes a start, and different - are attracted. At the painted magnet the North Pole is usually marked in red color. About a source of variation magnetic field the magnet will fluctuate with a frequency of its change, and a steel subject - with the doubled frequency.
3. For definition of a form of power lines of magnetic field use a transparent vessel with liquid oil in which there are particles of oxide of iron (rust). At present in a vessel will queue up to a magnet or an electromagnet of a particle parallel to power lines.
4. The coil and Hall's sensor belong to electric devices for definition of existence of magnetic field. The first reacts only to variation fields and to find constant with its help, move it in space. Hall's sensor reacts to any fields. For its use give food on the conclusions intended for this purpose, observing polarity. Supply voltage is specified in the passport to the device. Remove information on existence of the field from alarm conclusions. Remember that some sensors of Hall are linear, and others - discrete. The second react to influence in steps, without allowing to define its intensity.