What Is Electric Polarization?
Simply speaking, polarization is the alignment of opposite properties in different directions, called vectors. This phenomenon is seen in solids, liquids and even light rays -- think of polarized sunglasses. Polarization also plays a role in nerve signaling in the human body. Electric polarization refers to the aligning of the opposite charges within an object. It is a beneficial trait for capacitors, resonators and insulators.
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Charge Alignment
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Many molecules feature positively and negatively charged ends. These charges may be permanent, due to the electronegativity of the molecule's components or temporary, induced charges. Both permanent and temporary charges can be polarized, causing the positive ends to align on one end and the negative ends to align on the opposite side. This phenomenon can be demonstrated with a balloon and a wooden door or cabinet. Apply a negative charge to the balloon by rubbing it against your hair, then hold it up to the wood. The charges inside the wood will temporarily realign so that the positive ends are facing the balloon in response to the balloon's negative charge. This results in the balloon sticking to the wood.
Formulas
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There are several mathematical formulas that can be used to calculate electric polarization. The main one is P = (D-E)/4π. In this equation, P stands for polarization, which is calculated by determining the difference between the induced and imposed electrical fields, D and E respectively, and dividing that value by four times pi, which is symbolized π. Pi is a constant in math and is the ratio of a circle's circumference to its diameter.
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Charge Changes
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It is important to keep in mind that polarizing a molecule does not give that molecule a charge. Some molecules have positive or negative charges due to too few or too many electrons, but this is not what happens in polarization. These charged molecules can also be polarized and will continue to carry the same charge whether they're polarized or not. Polarization is merely aligning the charges already present within the molecule.
Capacitors
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Many capacitors are polarized, meaning the charges are separated into a positive region and a negative region. The charged regions are separated by an electrolyte. The main benefit of polarized capacitors compared with non-polarized capacitors is that polarized capacitors have a larger capacitance, or store capacity. Polar and non-polar capacitors each have separate uses and cannot normally be substituted for one another without causing damage.
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