Electricity Circuits

In this section of the course we looked at simple electrical circuits that would be found in the automotive electrical industry. Within this topic there were a few new terms and tests to do. These tests were done on four different types of electrical circuits: Individual, Series, Parallel and compound circuits. The results were then analyzed and compared with eachother to get an unerstanding of how each circuit works. A few terms to remember: Voltage, Ampere, Ohms, Wattage, Voltage drop, Available voltage.

What do these terms mean?
Voltage: Voltage is the force or pressure that is required to move the electrons (current) in a circuit.
Ampere (Amps): Ampere is the measure of current. The more current in a circuit the larger the reading and vise
verse.
Ohms: Ohms is the unit of resistance. This is the resistance to the flow of electrons (current).
Wattage: This is a measure of the power that is being used by a consumer to produce an output.
Voltage drop: This is a reading that shows how much voltage is being used up (consumed) by a component in the circuit.
Available Voltage: This is a reading that shows how much voltage is available to use at different points in the circuit.

Individual Circuits   
An individual circuit is a very simple circuit. It has only one consumer. Only one path for the electricity to flow through. This circuit was used to understand simple laws of electricity. The power supply was set to 12.73V. One law of electricity sates that the voltage supplied must be used within the circuit. In this case the voltage drop over the bulb was 12.71V. This means that the bulb was using this voltage to produce an output (work done), and in this case the output was light. The remaining voltage (0.02V) is being used up by the wires in the circuit to push the current through. This is caused by the internal resistance of the wires. In this circuit most of the resistance was caused by the bulb we used. This then affected the amperes (current flow) in the circuit (0.36A). By using a bigger bulb like we did in the following circuit the ampere reading changed to 0.77A. the reason being is the bigger bulb offers less resistance as it allows more current to flow through it. Since its the only consumer and a majority of the resistance holder, the overall resistance of the circuit is reduced. Therefore the current flow increases.

Series Circuits       
A series circuit is the same a individual circuit except it has more than one consumer. Both the consumers are wired one after another. Meaning there is still only one path for the electricity to flow through. This creates a flaw because if one consumer doesn't work or shorts out then the entire circuit wont work as the circuit is now open and electricity doesn't have a clear path to flow. There are two rules we follow when it comes to series circuits. The first rule is that the overall resistance of the circuit is the sum of each individual resistance the circuit has. E.G: If a series circuit has two light bulbs each with the resistance of 5ohms. The overall resistance of the circuit will be 10ohms (5ohms + 5ohms). The second rule is that the voltage is shared equally depending on the resistance of each individual component in the circuit. E.G: If there are two bulbs both with the resistance of 5ohms, the voltage used by each bulb will be 6V (12V supply). But if there are two bulbs with different resistance 5ohms and 7ohms the voltage used by each bulb will be different. (5ohms uses 4V and the 7ohms uses 8V). The ampere reading (current flow) in a series circuit will be lower to that of the individual circuit. This is because the overall resistance in a series circuit will be higher than the overall resistance of the individual circuit as the series circuit has more consumers (more load on the circuit). The more number of consumers in a series circuit the lower the current flow (ampere reading) as each extra consumer adds to the total resistance of the circuit. 

Parallel Circuits     
In a parallel circuit each consumer has its own power supply (positive) and its own earth (negative). This is good as it means that the circuit will still work even though one consumer shorts out. This is because electricity has more than one path to flow through and if one path is closed (short circuit) electricity will just flow through the other components, as there still is a circuit. There are two rules we follow when it comes to parallel circuits. The first rule is that the voltage over each individual consumer (each link of the circuit) is the same as the voltage supplied. E.G: If three bulbs are in a parallel with a power supply of 12V, the voltage drop over each bulb will be 12V. This is because each bulb will have its own power (positive) and earth (negative). The second rule is that the overall resistance in a parallel circuit is lower than the lowest resistance. E.G: If there were three light bulbs in parallel with different resistance (5ohms, 3ohms and 9ohms). The overall resistance of that circuit will be lower than 3ohms. Lower resistance means more current flow. That's why the current flow  in a parallel circuit is higher than the current flow in the series circuit. The overall current flow is higher but the current flow over each individual component is determined by its resistance. Electricity is lazy and will always try and take the easiest path. That's why you'll find that the current flow through a bigger bulb will be greater than the current flow through a smaller bulb. The bigger bulb offers less resistance than the smaller bulb and therefore more current flows through the bigger bulb. The more number of consumers in the circuit the greater the overall current flow, as the overall resistance of the circuit decreases. 

Compound Circuits    
A compound circuit is made up of part series circuit and part parallel circuit. Both the rules from the series circuits and the parallel circuits apply here. The parallel part of the compound circuit acts as one unit or one consumer. Since its in parallel the overall resistance of that part of the circuit will be low. Most of the resistance of the circuit will come from the components that are wired up in series (resistance = sum of all individual resistance). Since the parallel side of the circuit has lower resistance, the voltage drop (volts used) over that part of the circuit will be low and voltage drop over the components in series will be greater. The current flow in a compound circuit will be higher compared to the current flow in a series circuit. But the current flow will be lower compared to the parallel circuit. This is because the parallel side of the circuit acts as one consumer with a low resistance to flow. This affects the overall resistance of the circuit as it will be lower than a series but still higher than a parallel circuit.