Explaining how electrical circuits work can be quite a task. Probably because we are unable to see these little electrons – considering their 0.00282 pico-meter size. But lets imagine the three basic components of an electrical circuit: current, voltage and resistance. Let’s say current represents an army of soldiers, voltage represents the energy level of each soldier and resistance represents a high wall all the soldiers are expected to climb over to complete the course.
Current in the diagram above is illustrated by a small ‘e’. Each ‘e’ or soldier has its energy maxed in its barrack which represents the energy bank that the soldiers source their energy from. This energy bank is called the voltage source. After the current leaves the voltage source, it would follow the pathway (or course) that has been created for it – the pathway in electrical terms is constructed using wires. It represents a series circuit if it has one single loop otherwise a parallel circuit.
All the soldiers in a series pathway will travel the same route (of course because there is no other route!). The soldiers will determine how they are going to use all of the energy that they had received from the barrack before returning. In a complete course (or circuit) there has to be some obstacles or high walls that the soldiers have to jump over and they (the soldiers) will allocate portions of their energy to each wall depending on how high the wall or resistance is. Upon returning to their barracks all the soldiers would have completely zeroed their energy level so that they are able to refill to maximum their energies once again.
All the soldiers in a parallel pathway will travel the same route until they reach a junction (or split in the pathway). This junction in electrical terms is called a node. At the node, the soldiers will compare the resistance of each path and most will take the path that poses the least resistance – only a few will take the path of high resistance but all soldiers will eventually use the same energy once they reunite at another junction later down the pathway. Upon returning to their barracks all the soldiers would have completely zeroed their energy level so that they are able to refill to maximum their energies once again.
We use three devices to measure each of the three basic components of an electrical circuit. These are: ammeter for current, voltmeter for voltage and ohmmeter for resistance. We place the voltmeter and ohmmeter across the section of the circuit we want to measure, however we place the ammeter inside the circuit at the point we want to measure.
Ohms Law and Kirchhoff’s Current and Voltage Laws govern the properties of electrical circuit behavior. Ohms Law states the Voltage = Current x Resistance. Kirchhoff’s Current Law states that all current entering a node (remember, a node is a junction in the pathway) is equal to all the current leaving the node. Kirchhoff’s Voltage Law states that the sum of voltage drop across resistors in series is equal to the source voltage. The next post will elaborate on these laws.