You likely have heard the term ‘anode’ when talking about a battery. In this lesson, we’ll define what an anode is, how it functions as part of a system, and some easy ways for you to recall what an anode is.
What Is An Anode?
An anode is one part of a component that makes up an electric circuit. So let’s start with some basics of an electric circuit so we can really understand what an anode is and how it fits into the bigger picture.
A Simple Look at Electric Circuits
Very simply, an electric circuit is a system in which electric current, which is defined as the flow of electric charge, flows through a conductor. The conductor is usually something simple like a copper wire, but can also be something more complicated like a liquid or gaseous solution, which is called an electrolyte.But what causes the electric current? If I connected a wire end to end in a loop, would electrons flow through the wire?The answer is no, and the reason is because with just a conductor, we don’t have anything that’s driving the electric charge to flow.
So, how do we get electric charge to flow? We do that by adding a component to the circuit that provides what’s called electric potential.Electric potential is a simplified way of describing the potential energy an electric particle has due to its location. To really understand this principle, we can make an analogy to gravity.Let’s think of gravity very simply as an energy field.
By being near the Earth, objects with mass, including ourselves, experience the effects of that gravitational energy field every day. We’re pulled down towards the Earth. We have a way of quantifying those effects by calculating the energy required to get to certain physical locations in the gravitational field, and it’s the equation for potential energy (PE), which is:PE = m*g*h (Equation 1)where m is the mass of the object, g is the acceleration due to gravity of an object, and h is the height of the object.So, what does this equation tell us? It tells us that if we, with our mass (m), are at a certain height (h), we’ll have a certain amount of potential energy (PE).
Another way of thinking about this is that if you want to get yourself with your mass to a certain height, something has to provide the required amount of energy to get you there. Think of it like climbing a mountain – if you’re at the top, you put in a lot of energy to get there because you fought the gravitational field of the Earth all the way up!Electric potential is a lot like gravitational potential. It describes the amount of energy a particle has based on its location. It’s a way of quantifying how much energy the particle was given to make it move against an electric field. In the case of our electric circuit, that field is the field created by the repulsion of the electric particle to other like particles. So, just like our mountain climbing situation, we’re describing a particle that pushed its way through an electric field to get to where it is!
How Anodes Fit Into An Electric Circuit
How does this relate to an anode? An anode is one part of a device in an electric circuit in which electrons build up and leave through the conductor.
Let’s talk about a very specific example that we’re all probably familiar with – a battery.A battery works by housing an electrolytic solution and two conductors at each end, as shown in the Figure 1 below. For our purposes, we’ll say that the bottom end is the anode and the top end is the anode’s opposite, which we call the cathode.
A chemical reaction inside of the battery causes electrons, which are negatively charged, to gather at the anode, and protons, which are positively charged, to gather at the cathode, as shown in Figure 2 below:
As you can see, we’re getting closer to having all the components we need for our electric circuit.
The electrolyte in the battery creates an electric potential difference and a driving force for current to flow. All we need to do is connect the two ends of the battery, and we’ll have electrons flow from the anode to the cathode, as you see in Figure 3 below:
Now that we’ve got our electric circuit set up, we can really understand what the anode is.
Inside the battery, electrons are building up on the anode. When the anode and cathode are connected by a conductor, electrons, driven by the potential difference between the anode and cathode, flow from the anode to the cathode.Pretty simple, right? Not so fast – there a few peculiar aspects that you’ve got to keep in mind, but all of which are easy to work with now that you’ve got the basic set up.First, let’s talk about the direction convention that we use for current. In our set up, we’ve got electrons flowing out of the anode towards the cathode. But, we define the current flow as opposite the direction of the flow of electrons.
That means that the current is flowing INTO the anode, because electrons are flowing OUT of the anode. A common mnemonic for remembering current flow when talking about anodes is: ACID, or Anode Current Into Device. But remember, current flow is the opposite of electron flow, which means electrons are flowing out of the device through the anode.Secondly, let’s talk about the device itself. In our example, we’ve got a battery, which is a device that provides electric power. What if the device we were talking about was one that *uses* power?Let’s think about our battery not as one providing power, but as one being recharged by another battery.
We still stick with our mnemonic ACID, again which tells us that the anode is the part of the device that current flows into. In the cases of the rechargeable battery, the anode will be the positively charged side.
In review, an anode is a component of a device that provides an electric potential difference as part of an electric circuit. The anode is the part of the device where current is flowing into the device – it’s most easily remembered by the mnemonic ACID (Anode Current Into Device.)