Continuing from “Basics of Circuits Part 1- Charge and Conventional Currents”, we will now explore three essential concepts needed to understand circuits. As stated in part 1 of this exploration, we will use the concept of Conventional Currents, which tracks the flow of protons, as it is considered a standard. These are voltage, current, and resistance. We will first start by establishing the concept of voltage. Since these topics may be hard to grasp, we will illustrate this using an analogy to plumbing using the concepts of a water pump, water pipes, and water clogs as when we think about the flow of water through our homes, there are many similarities.
In terms of one of its formulas, we can define the voltage as the change in electric potential energy per unit of charge. A charge gains electric potential energy when placed nearer to like charges, as the charge usually repels large charges. According to the equation delta-v = deltaUe/q, where delta-v represents potential difference(voltage), delta Ue represents the change in potential energy, and where q represents both the magnitude and sign of the charge voltage is a positive amount, a charge goes towards areas where the charges are positive and a negative amount when the charges go towards areas where the charges are negative. Also, voltage is measured in volts. Now, we will consider the idea of a battery. As we know, a battery contains both a positive side and a negative side. Now, assuming the flow of protons in a battery, the proton would be pushed up to the positive side. This is known as voltage gain, as the voltage would be increased. The proton would then be released from the positive side and travel through the wire and travel to the negative side of the battery. This is very fascinating. Although we use batteries in our everyday life, such as putting them into our remote controls or powering watches, we never really think about how they work. Now, this helps show how batteries fuel the process of circuits, which is in fact how these everyday objects work. In terms of the plumbing analogy, think of a battery as a water pump, which allows the water to flow in the first place. Likewise, a battery provides the energy for protons to flow. Voltage drops happen when these protons travel through resistors(think of televisions, computers, fans, etc) which convert the electric potential energy into other forms of energy that provide resistance(we will talk more about this later) and the decrease in electric potential energy results in a decrease in voltage. Think about it. The electricity comes from the outlet on our walls. We usually plug in many things from toasters to television sets into the walls, and this allows for the initial electric potential energy to power electronics. According to the conservation of energy, the voltage drops have to be equal to the voltage gain. As we can see, a battery is required to provide voltage gains to protons so that the circuit continues to run.

Now, we will talk about current, which is luckily a more straightforward topic. Current is the rate of charge passing through a wire. In the plumbing analogy, think of this as the water flowing through the pipes. The idea of current is shown using the equation I=delta Q/delta t, where I represent current, delta-v represents the change in charge, and delta t represents the change in time. Current is measured in Amps. Because of conservation of charge, the current remains the same. Like how water has to flow through pipes, charges require a medium of their own to flow through which is usually wires.

Now we will talk about Resistance. Resistance hinders the flow of protons or current in a circuit. It is measured in units called Ohms. Resistance is usually caused by resistors, which inherently causes a hindrance to the flow of protons by using the electric potential energy into other forms of energy such as heat. Resistance can also be caused by some resistivity in the materials of the wires themselves, which could also hinder the current in the circuit. In terms of the plumbing analogy, this can be represented in multiple examples. Clogs in pipes, for example, represent resistance as a clog would hinder the flow of water. Resistance can also be shown through the idea of sinks and showers as this also hinders the flow of water by causing some of the water to be put into other uses.

The different concepts of voltage, current, and resistance are connected by one equation, known as Ohm’s Law. This equation states that delta V=IR, where delta-V is voltage, I is current, and R is resistance. This is a useful equation in determining different circuit problems in which you have to determine the voltage, current, or resistance of different portions of a circuit. This equation is more used in problem-solving questions related to circuits in which you essentially fit different pieces of a puzzle using this equation in specific situations, to get all the information you need. Now, you have learned the basics of how circuits work and operate and I hope this has expanded your intrigue into how everyday situations such as turning on lights or charging your phones work.