Polarity (physics)

The term polarity refers to the supplying or arrangement between two poles ( opposite extreme points) in space.

This may be, for example:

• Pole of an electric potential difference ( voltage, for example a battery)
• The alignment of the two regions on a magnet, in their environment, the magnetic field strength is particularly high, see magnetism
• Anode and cathode of a diode and their location during installation
• Terminals of an AC voltage source with respect to their phase position (inverted or non-inverted)

The polarization in this context means the formation of opposite charge in an insulating material body due to an inhomogeneous charge distribution. The polarization direction ( transverse, antennas, electromagnetic waves, light), however, has only indirectly related to the polarity.

Molecules are polar if they have differing charge centers of their positive and negative charges, see polarity (chemistry).

If the two a / b wires of an analog telephone connection in b / a polarity, a simple phone still works, even though the phone line voltage ( 60 V) is applied. The polarity or polarity is - as with AC loads to the mains - not matter.

In contrast, the polarity is mandatory in the following cases or important:

• Series or parallel circuit of transformer windings ( AC voltage out of phase or in phase )
• Assignment of the three phases in the three-phase (determines the direction of rotation)
• Polarity or polarity of a diode; see also rectifiers, free wheeling diode
• Polarity of a battery ( automotive, battery-powered devices )

With a double switch or an H-bridge can reverse the polarity of a voltage source.

• Physics