Basic concepts of electronics are:

Atoms and Electrical Charge  - Discusses the structure of atoms. 

 Current -  Introduces current and ampere.

Voltage
- Potential difference and voltage.

Power
- Discusses power or the amount of work a circuit is doing.

Resistance
- Discusses electron flow, materials, and the ohm unit.

Ohm's Law
- The relationship between Current, Voltage, and Resistance.

 Atoms and electrical charge

Atoms are the building blocks of all matter. They are made up of protons, neutrons, and electrons. Every electron has a small negative (-) charge. The proton has the same amount of charge except that it is the opposite, positive (+) charge. Neutrons are electrically neutral and have no charge. The protons and neutrons are located in the center of atoms forming what is called the nucleus and the electrons revolve around them.

It is very important to know that particles of like charges will repel and unlike charges will attract. For example, two protons or two electrons will repel each other. However, a proton and a electron will attract. That is how the electrons are held inside the atom. The attraction between the electrons and protons keeps the electrons in orbit much like the gravitational attraction between the sun and its planets.

Electric Current

Electric current is the amount of electrons, or charge, moving past a point every second. It is basically the speed of electron flow. The faster the electron flow, the higher the current.



Current is represented by the letter I. The basic unit for measuring current is ampere. Ampere can be abbreviated to amp or just A.

1 amp = 1 coulomb/sec
Meaning for every amp, there are 6.25x10^18 electrons moving past a point every second.

Ohm's law

Ohm's law is one of the most important concepts in electronics. Fortunately it's only a very simple mathematical relationship between current, voltage, and resistance.

According to the Ohm's law, voltage equals current times resistance which is expressed in the following equation:

E=IR
where E = voltage, I = current, and R = resistance

For example, if
I = 0.1A
R = 10k
then
E = 0.1 * 10k

E = 1000 volts

Note: "k" stands for "thousands". So 10k = 10,000 ohm

Power

Power is simply the amount of energy used or the amount of "work" a circuit is doing.

Power is represented by the letter P. The basic unit for measuring power is watts or the letter W. To find power, all you need is a simple equation:
P=EI
or Power equals voltage times current.

For example, if
E = 9V
I = 0.5A
then
P = 9 * 0.5

P = 4.5W

Resistance

To better understand what resistance is, you must first get an idea of how electrons flow.

When an electron is knocked out of an atom, it will fly off and hit another atom. If the electron strikes the atom with enough force, it will knock off another electron. The atom that was just knocked off will hit another atom and so forth.


Note that every time an electron strikes another, it is transferring its energy. Some of the energy is converted into heat every time it is transferred. The voltage will drop as the energy is transferred over long distances. Thus a long wire has a higher resistance than a short wire.

Some materials - such as copper and silver - does not hold on to its electrons very tightly. Therefore it doesn't require much energy to knock off an electron. These materials are called conductors and has a very low resistance to electron flow.

Materials such as clay and plastics hold on to their electrons more tightly than conductors. It takes more energy to knock off an electron from these materials. These materials are called insulators and has a high resistance to electron flow.

Now, you must understand that this is NOT how electrons really flow; It serves only as something for you to work with. To really know how electrons flow, which we will not get into, you will need to study quantum physics.

Resistance is represented by the letter R. The basic unit of measure is ohm or the symbol (Greek omega).

In the next section (Ohm's Law), we will show you the relationship between Current, Voltage, and Resistance. Resistance will also be further discussed as we introduce the resistor.

Basic knowledge
of Electronic parts



Click on them to get more information about them.

Resistors	Coils
Capacitors	Printed Wiring Boards
Diodes	Relays
Transistors	Wiring materials
Integrated Circuits