Sourcing and Channelling Electricity
Part 1 | Part 2 | Part 3 | Part 4
Electronics is all about controlling the flow of electrons in a circuit to shape the electrical energy delivered to a load in just the right way. Simply put electronics makes electricity better,
Today we will be exploring a simple electrical circuit to learn about how to get electrons flowing and get to grips with the direction of current, that way we can learn how to shape and direct current in our own circuits!
Finding a source of Electrical Energy
Like humans needs food to keep going, Electrical circuits need a source of electric energy to get electrons flowing . Sources of electrical energy take another form of energy such as chemical, heat, mechanical or light energy and convert it.
As it turns out, exactly how electrical energy is generated by a particular source is important because different sources produce different kinds of electric current: Direct current also known as DC and Alternating current aka AC
Direct Current 🔋
Direct current is a steady flow of electrons in one direction with minimal variations in the strength of the current, most circuits use DC, DC is usually sourced from cells more commonly known as Batteries.
Cells are made by immersing two different metal plates are immersed certain chemicals, metal atoms react with the chemical atoms to produce charged particles. Negative charges build up on one metal plate and and Positive charges build up on the other metal plate the difference in charge across the plates formally known as terminals, creates the force needed to push electrons through a circuit. This force is the one we previously identified as voltage and the reaction above is known as an electrochemical reaction.
When using a battery in a circuit you connect your load e.g a Light Emitting Diode to the negative terminal also known as the anode and to the positive terminal known as the cathode, in doing so you create a path that allows the energy to move, this path is a basic electrical circuit.
Because electrons move only in one direction the current generated by a battery is Direct Current.
In electrical diagrams the following sign is used to represent a battery
Alternating Current 🏭
We don’t always use batteries! Sometimes we use other sources such as the sockets on our walls.
Well when you plug a light into an electrical socket in your home, you’re using electrical energy is generated from a power plant. Generating plants convert energy from resources like coal and water into electrical energy.
The fact that electrical energy is created by converting a form of energy is why electrical energy is said to be a secondary source of energy
In Hydroelectric power plants water pressure is used to spin turbines which are connected to electromechanical generators which convert the motion of the turbine into electrical energy.
A generator contains a coil of wire inside a huge magnet. As the turbine rotates it turns the coil of wire and electrical current is induced inside the wire. Induction means that something is causing electrons to flow without any direct contact with the wire.
As the coil rotates inside the magnet, the magnet first causes the electrons to flow in one direction but when the coil is rotated 180 degrees the magnet pulls the electrons in the other direction and they go back again and voila this rotation creates an alternating current.
The symbol used in circuit diagrams for an AC voltage source is shown below
Getting clear on the Direction of Current ▶️
Really early on it was believed that current was the flow of positive charges so electrical charge was understood to flow from positive to negative.
Much later electrons were discovered and it wad determined that they flow from negative to positive but by then the positive to negative convention had already become too well used and the standard became to depict the direction of current with an arrow that points to the opposite of the actual electron flow.
Exploring a simple LED Circuit 💡
In the following circuit diagram the battery is supplying 1.5V to the circuit. The plus sign indicates the positive terminal the minus sign the negative terminal.
The battery supplies electrical energy and the Light Emitting Diode uses electrical energy. A give and take relationship exists between the two. Voltage is the push the battery gives to get current moving and the energy for that push is used up as current moves through the LED and is dissipated as heat and light.
When you drop voltage through an LED or other such component the voltage where the current enters the component is higher than the voltage where the current exits the component.
Voltage at any point in a circuit is always relative to the voltage at some other point, usually the negative terminal of a battery
As you travel around a DC circuit you gain voltage going from the negative terminal of the battery to the positive terminal and you lose voltage as you continue in the same direction across circuit components by the time you get back to the negative terminal all the voltage has been lost and you are at 0 volts
Controlling Electrical Current
Controlling electrical current is similar in many ways to controlling water current, you can do things such as:
- Restrict the flow of current
- Cut off the flow of current
- Adjust the pressure of the current
- Allow only one direction of flow of current
Although comparing electric current to water current is helpful, water doesn’t need a closed system to keep flowing where electricity does.
Components to Control Flow
- Resistors — Resist the flow of current by a from going above a certain value
- Capacitors — Store electrical energy, envision dams that capture streams
- Inductors and Transformers — Store electrical energy in magnetic fields
- Diodes — Restrict the flow of current in a direction, much like valves
- Transistors — Can be used to switch currents on or off or to amplify currents
We cover all these components in more detail in later blogs in this series
Types of Circuits
Exactly how you connect components together dictates how current flows through your circuit and how voltage is dropped throughout the circuit.
Series Connection
In this type of connection current flows from the positive terminal through a closed switch then through a number of components one after the other then back to the negative terminal. This arrangement is serial, i.e each component gets energy after the one before it, hence the circuit is known as a series circuit and it has the following qualities
- Each component has the same current
- Voltage from the source is divided up among the components
Parallel Connection
In a parallel circuit current flows from the positive terminal then splits at each branch of the circuit, so that each load gets the a share of the the supply of current the current flowing through one load does not travel through other loads. Parallel circuits have the following qualities
- Voltage across each branch is the same
- Current supplied by the source is divided among the branches, the current in each branch adds up to the total supply of current
Combination Circuits
Most circuits are combinations of series and parallel connections, How you arrange components in a circuit depends ultimately on what you are trying to do!
And thats it! You now should now have a firm grasp of:
Where to find electricity
Which type of electricity to use
and last but not least basic circuit types
In the next part we look at Meeting up Resistance
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Back to soldering! 🔌
