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Electricity! What is it and How Does it Flow? By Cooper Remkes, Student, Weber State University College of Science Physics Department, April 2012


There are many misconceptions about electricity, but the two I would like to help clear up are: What is electricity and how does it flow? The misconceptions here deal with what is actually flowing when electricity is created and which direction it goes.
In order to address this issue, a few preliminary terms need to first be defined:

Electric Current - The "flow" of electricity
Voltage - The "push" of electricity
Resistance - The ability of something to allow electricity to flow. High resistance means electricity won't flow easily and low resistance means it will flow very easily
Net Charge - If a particle is not neutral then it is either positively or negatively charged. A net charge occurs when there is more of one type of charge than the other
Electrons - A part of an atom. They are negatively charged particles
Protons - A part of an atom. They are positively charged particles
Ions - Charged particles. Electrons and protons are both ions even though they have opposite charges
Open Circuit - An electrical circuit that is disconnected somewhere and electricity cannot flow
Closed Circuit - An electrical circuit that has a connected path (a loop) through which electricity can flow

==What is Electricity?
==
To put it simply, electricity is a form of energy. It is present when a net charge either builds up at one location or moves from one location to another. When electricity is discussed in science classes, the concept of electrons is usually not far behind. Many people have a decent idea about what an electron is. They know it is something REALLY small and when there are a bunch of them, we can get shocked. That's not too bad of a way to describe electrons, but many times this idea of electrons creates the common misconception that electrons ARE electricity. The fact that the name "electron" sounds so similar to "electricity" doesn't help clear up this confusion. The reality is there are many other things that make electricity besides electrons. In other words, there are many other ions (charged particles) that can build up a net charge at one location or transport a net charge from one location to another. For example, if there was a build up or movement of protons, electricity would be there as well. In the next section, the situation where moving ions is discussed to clear up confusion about the flow of ions and the concept of electric current.

How Does Electricity Flow?


The flow of electricity is called electric current. When the term "flow" is used, it is easy to think of things (ions in this case) moving in a path, such as through a metal wire. The reason I suggest a metal wire is because most metals have very low resistance, and electricity can therefore easily flow through them. There is also direct current and alternating current. In direct current the flow of ions is on one direction only, while in alternating current the direction changes back and forth rapidly. Electricity is present with both types of current (because net charges are moving from one location to another) but I will only talk about direct current on this page because of its relative simplicity. Even with direct current tough, there is a lot of confusion that develops when talking about the direction that the current is flowing.


Simple Battery Circuit
Simple Battery Circuit

The diagram above is a drawing of a closed circuit that has a battery connected to a lightbulb. The arrows drawn represent the direction that the electrons are moving through the green wire. The negatively charged electrons are attracted to the positively charged side of the battery and they experience a voltage (a push). Since the circuit is closed and there is a sufficiently strong voltage, the electrons are propelled along the wire through the lightbulb and back to the battery again. Now the question is, which direction is the current flowing? If you thought from the negative to the positive side of the battery (clockwise), you too have been deceived by this common science misconception.

Electricity flows OPPOSITE of the direction of NEGATIVELY charged ions (electrons in this case). So, quite literally, many little tiny electrons are traveling from the negative side of the battery to the positive side, but the flow of electricity is moving the opposite direction. This concept can be hard to grasp. So what happens in the situation of moving positive ions? Electricity flows the SAME direction of POSITIVELY charged ions (like protons)! This is conceptually much easier to understand, but the problem is that protons don't move in solids, only electrons. Thus, the correct idea of electricity flowing can be a very slippery subject to grasp.

Since the idea of electricity flowing the opposite direction of the movement of electrons is so confusing, many science teachers add to the confusion of which way the ions are flowing in order to simplify the concept of current. They tell their student to "pretend" that imaginary positive ions (instead of electrons) are moving counter-clockwise and that the current flows along with them. This simplifies the problem and helps the students understand the direction that the current is flowing. Theoretically there would be no difference, as positive ions that have the same net charge moving the opposite direction would create the same current, but in reality this is not what is happening at all.

It is also worth mentioning a few more things. There are situations where positive ions ARE the things that are moving instead of negative ions like electrons. Positrons for instance are positively charged electrons and when moving create a current that flows in the same direction of the ion's movement. There are also situations where negative ions and positive ions are both are allowed to move. In these situations the positive ions would move along with the current and the negative ions would move opposite the direction of the current.

Why is this important?


Understanding the direction of the flow of current is important for several reasons; I'll write about two. Most practically, it is because many common devices in electronic design (such as diodes and light emitting diodes (LEDs)) only allow electricity to flow easily one direction. That or they can be destroyed if electricity goes the wrong way. Another reason why this is important is because of Maxwell's Equations and the basis of electrodynamics. James Maxwell combined several equations together and discovered that changing electric fields creates magnetic fields and changing magnetic fields create electric fields, and the directions of the fields are related to each other and are significant (they determine which direction the force on an ion would be. For further understanding, research the "Right-Hand Rule" for determining the directions of the force based off of the electric field and the magnetic field). This discovery ultimately established the basis of science's understanding of electromagnetic radiation or in a more familiar term, light.


Conclusion


To summarize:
  • Electricity is a form of energy that is present when a net charge is either built up at one location or moves from one location to another
  • Electricity can be created by negative ions (such as electrons) or positive ions (such as protons)
  • Electricity flows OPPOSITE of the direction of NEGATIVELY charged ions and the SAME direction of POSITIVELY charged ions
  • It is helpful to "pretend" that imaginary positive ions are flowing from the positive side of a battery to the negative side, but remember that the reality is likely that electrons are moving from the negative side of the battery to the positive side

Hopefully this wiki page has helped you to better understand the truth about what electricity is and how it moves.