Basic electronic concepts

I am going to attempt to explain some of the basic concepts involved with electronics in this page, most of this information will explain 'why?' electricity behaves like it does and will probably not be too useful if your just going to attempt to make the projects on this site. If you want to design your own circuits however, you will need to understand how electricity works and this will enable you to intergrate components in order to control electricity. By doing this you will gain an understanding of electronics.

Basic Concepts

• Voltage (V): Voltage is a term used to describe potential difference (pd). It is a measure of electrical potential energy converted to another form for every unit charge moving between two points in a circuit. So put simply it is the strength of the electric charge. Emf (Electromotive Force) is another term used to describe voltage.
• Current (I): Current is the flow of electrons through a circuit due to the presence of a potential difference (Voltage). The current at any point of a circuit is the amount of charge flowing per second; it is measured in ampres (coulombs per second). Current may be DC (Direct Current) such as that found in a battery or AC (Alternating Current) such as mains voltage.
• Resistance (R): Resistance is the property of a substance that restricts the flow of electricity through it. Different materials have different reistances, a material with a high resistance is called an insulator and a material with a low resistance is called a conductor. Metals are the only conductors (except for graphite). The unit of resistance is the ohm.
• Ohm's law: Law that states the current flowing in a metallic conductor maintained at a constant temperature is directly proportional to the potential difference between its ends. Ohms law states that: V=I*R, I=V/R and R=V/I. Discovered by Georg Ohm in 1827.
• Power: The rate at which a machine or component converts electricity into other forms of energy. Power= electrical energy converted by the machine over time or by: P=I *V
• Frequency: Frequency is the number of periodic oscillations occurring per unit of time. The unit of frequency is the hertz (Hz). One hertz is the equivalent to one cycle per second.
• Polarity: Polarity is an indication of which pole the components are connected to in relation to the power source. There is Negative (-) and Positive (+). Some circuits may not show all the appropriate connections made to the negative pole (0V) and instead may use a 'ground' symbol. The ground symbol is a set of three lines and indicates 0V- this just reduces the amount of wires shown in a circuit diagram and makes it clearer.

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