Anode vs Cathode
Anode and cathode are two terms that are often used interchangeably with positive and negative in batteries. Most of the time there is no problem with it as the definition would often match the practice. However, there are certain scenarios where this is not true.
The anode, by definition, is the electrode where electricity flows into. In contrast, the cathode is the electrode where the electricity flows out of. If we look at a battery connected to a load, like a bulb for example, the electricity flows from the positive terminal to the negtive terminal. In this case, the positive terminal is the cathode, and the negative terminal is the anode. But when the battery is being charged, the electricity flows into the positive terminal instead of out of it. In this case, the roles are reversed, and the positive terminal becomes the anode and the negative terminal is the cathode.
The reversal is also very noticeable when you are dealing with components like diodes and capacitors since these components absorb electricity unlike batteries. The anode of capacitors and diodes is the side that you connect to the positive terminal since that’s where the electricity enters, and the negative terminal is the cathode because that is where the electricity leaves.
Because of the confusion with regards to the current flow and where the anode and cathode is, it is probably better to use the terms positive and negative terminals instead. It is constant and doesn’t change regardless of the current flow.
Aside from being used together, there are also applications where they are not together. A good example of this is the sacrificial anode coating, usually zinc, used to protect metals. This is common in ships where the flow of water creates a static charge. The sacrificial anode absorbs this charge and slowly disintegrates. In this manner, the underlying metal doesn’t get damaged, and only the coating needs to be restored every so often.
Summary:
1. The cathode is typically the negative side while the anode is the positive side.
2. The anode is the electrode where the electricity flows into it.
3. The cathode is the electrode where the electricity flows out of it.