Thursday, October 11, 2012

Basic concept of electricity

Electricity is a form of energy. Electricity is the flow of electrons. Every material, be it solid, liquid, or gas contains two basic sub-atomic particles that house a fundamental property known as electrical charge. These particles are the protons and the electrons. The proton and electron each contain the same amount of electrical charge, however their type of charge is exactly opposite of each other. We distinguish the two by defining the proton’s charge as positive (+) and the electron’s charge as negative (-) . Electricity is simply the movement (or “flow”) of the electrons.

The electrons of different types of atoms have different degrees of freedom to move around. With some types of materials, such as metals, the outermost electrons in the atoms are so loosely bound that they chaotically move in the space between the atoms of that material by nothing more than the inffuence of room-temperature heat energy. Because these virtually unbound electrons are free to leave their respective atoms and float around in the space between adjacent atoms, they are often called free electrons.
In other types of materials such as glass, the atoms’ electrons have very little freedom to move around. While external forces such as physical rubbing can force some of these electrons to leave their respective atoms and transfer to the atoms of another material, they do not move between atoms within that material very easily.
This relative mobility of electrons within a material is known as electric conductivity. Conductivity is determined by the types of atoms in a material (the number of protons in each atom’s nucleus, determining its chemical identity) and how the atoms are linked together with one another. Materials with high electron mobility (many free electrons) are called conductors, while materials with low electron mobility (few or no free electrons) are called insulators.

Electric Current:
The Electric Current is a flow (movement) of electric charge (electron) through a conductive material (circuit) from a point with a higher electrical potential (voltage) to the other.

The value of current or the current intensity is equal to the volume of the flowing electrical charge in the unit of time, second, as shown in the formula below: I = Q/t
Were I is the electrical current, which we refer to as Current, Q is the positive electrical charge in Coulomb (the electrical charge unit) passing in the time t with the unit of seconds.

Voltage (also called electrical potential difference or electric tension or electromotive force) is the potential energy that makes the electrical current flow in a circuit by pushing the electrons around. Voltage is equal to the work which would have to be done, per unit charge, against a static electric field to move the charge between two points.
Voltage can be direct or alternating. A direct voltage maintains the same polarity at all times. In an alternating voltage, the polarity reverses direction periodically. The number of complete cycles per second is the frequency, which is measured in hertz (one cycle per second), kilohertz, megahertz, gigahertz, or terahertz. An example of direct voltage is the potential difference between the terminals of an battery. Alternating voltage exists between the terminals of a common utility outlet.

The unit of voltage is volt shown as ‘v’.  One Volt is equal to one Joule of energy that can move one Coulomb of electrical charge. A voltmeter can be used to measure the voltage (or potential difference) between two points in a circuit.

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