How to determine the pole
Magnets, electromagnets, and the DC voltage source devices with unilateral conductivity have two poles. In the first case, these poles are called the north and south, and in the second - negative and positive.
Instruction how to determine pole
To determine the magnetic poles take the second magnet pole which are designated by letters (of N - north, the S - South) or colors (red - north, green, blue or gray - South). North Pole test magnet is attracted to the south of the test, and vice versa. Test and test the magnets must be of approximately equal strength, or possible reversal of the one who is weaker. When dealing with strong magnets, be careful not to get injured mechanical fingers.
To determine the polarity of the rectifier element with unilateral conductivity connect the ohmmeter first one and then the other polarity. The element itself at the same time should be de-energized. If the probe, on which there is a negative voltage will be connected to the cathode and a positive voltage to the probe - to the anode, the instrument will show the resistance is much less than infinity. In analogue instruments voltage polarity in ohmmeter mode is usually the opposite polarity of the voltage that should be applied to the same schupam in voltmeter mode. At the same digital devices these polarities often coincide. If in doubt, check the device on the diode, the location of which is known findings.
To determine the pole of the DC voltage, connect the voltmeter, which previously exhibited the appropriate limit. If the source generates a voltage of 24 V, at the same time observe the safety rules. voltmeter probes have the following colors: black or blue - minus, white or red - plus. In analog voltmeter when polarity arrow deflected slightly to the left and rested in the limiter, while the digital - to display a minus sign appears in front of the number. Note that when properly chosen limit the force applied to, can be so great direction that the latter will pursue.
The poles of an electromagnet defined in the same manner as the magnet pole. If you change the polarity of the supply voltage are swapped. If the solenoid coil is wound clockwise, the negative terminal will meet the north pole and the positive - the south. In an electromagnet coil which is wound counterclockwise, the opposite poles of the appropriate conclusions. Even if the coil is powered low voltage, beware of self-induction pulse generated at the time of current interruption.