Electricity principles and technology

SCIENCE IN ACTION

By MICHAEL JOHN UGLO
THIS 11th lecture is on electricity principles and technology in the science in action series. Welcome to you all to this indispensable topic and happy learning. The advent of electricity revolutionised human life through recorded history.
Credit is owed to the innovator and inventor. If PNG includes innovation and breakthroughs in its approach to development aspirations and agenda, then we are appropriately tuned because that will enable us to be prosperous and competitive in comparison to the rest of the countries in the world particularly the technologically advanced countries.

The technologically advanced countries sell to us very highly priced technologically advanced goods which belittle us and make us become subordinate.
A demonstration is that we buy an aeroplane with millions of kina. Also a fighter plane costs billions of kina. Notwithstanding, the scenario will change when we innovate or come up with a product that is not known to the world and is in a demand and is able to be picked up around the world. Here we will fare very well and will be able to bring in a lot of money beyond our conventional export products that sell but do not bring in windfalls. This is the next economic stage PNG wants to lead.
Electricity principles
Electricity is flow of electrons. When electrons flow, they can do work such as lighting up a room, cooking food, washing clothes through washing machines, send information across mediums such as radio and television. Electrons are tiny sub-atomic particles that carry a negative charge. That charge is given a unit called a coulomb. So, an amount of the flow of electrons through a conductor is measured as a coulomb per second, called an ampere or amp for short.
The pressure needed to move one coulomb per second over one ohm is called a volt or voltage in full. Voltage is the infinity of distance travelled by one positively charged particle to have one volt ready for an electric field to have access to it. In the flow of electrons, they can encounter resistance to overcome in order to flow. The resistance is measured in a unit called an ohm or ohms.
In direct current (DC) voltages, the above relationship is best given in the equation called the Ohms Law. This law states that voltage is equal to current multiplied by the resistance. That is V = IR or V = I x R. In some textbooks, the symbol V for voltage is given as E which means energy. The voltage is called potential difference and is based on the fact that it was an infinity of distance travelled by one positively charged particle to get to an area where an electric field can have access to it.

The positive current flows from an area of higher potential to an area of a low potential that is essentially basically the flow of conventional current around an electric circuit. An electric circuit is a closed loop that provides for the flow of the conventional current as well as the electrons around it. An electric circuit normally has electrical components like a power source such as a battery, a connecting wire, a switch and loads such as a lamp or light bulb.
The power source is the source of voltage that is high enough to flow or diffuse from an area of higher concentration and that is from the positive terminal to an area of lower concentration and that is the negative terminal and that basically is around the circuit. This is the flow of the conventional current. The flow of electric current (normally referred to as just current) happens in the opposite direction. That is, it flows from negative to the positive terminal of the battery or a DC source of power supply.
Electric current is generated when the voltage is moved over a particular magnitude of resistance. So, the relationship is, electric current increases in an indirect proportion or inverse relation to the resistance when more or less resistance is encountered given the same voltage. When resistance is lowered, conventional current will flow increase and more electric current is produced and vice versa.

In an alternating current or AC current it has two parts to a flow of current. It has a positive and a negative current which both flow in the opposite directions. The AC current takes the form of a sine or a sinusoidal wave form to transmit electrical power or electrical energy.
Power loss is measured when the electric current is doubled and multiplied with the resistance. That is Power (P) measured in watts equals current squared times resistance. That is P = I2 x R The power transmitted is equal to the current multiplied by the voltage. That is P = I x V.
The average for the value of an electric current is normally referred to as root mean squared (rms). That is, comparison is made in a DC source of voltage with that of the AC referred to as rms. For a DC voltage of 240 volts, the average sinusoidal frequencies of AC voltage must approximate the root mean square of 240 voltage. That is the reason, that in an AC current the reading is an approximation of the mean value as compared to a DC.
The electronic transmissions are all done in an alternating current as the negative and the positive sine waves carry the information depending on the various wavelengths and the frequencies.
The information is modulated with a carrier wave with its frequency or its phase to transmit. At the receiving end, there is the receiver circuit with the capacitors and the inductors.
The vacuum tubes, diodes, transistors, integrated circuits, capacitors and inductors have the ability to display the invariability of the electric currents. This has enabled the electronic industry to process signals, process information and transmit data over networks and devices
My prayer for PNG today is: “In His wisdom He strengthens us, like gold that’s tested in fire, always ready to seek the lost, to answer those who pray.”
Next week: The technology and sciences of fluids

• Michael Uglo is the author of the science textbook “Science in PNG, Pacific, Asia & Caribbean” and a lecturer in Avionics, Auto-Piloting and Aircraft Engineering. Please send comments to: [email protected]