Electrodynamics in technology


IT is the aim of this lecture to break down the highly specialised study of Electrodynamics like we did for Astrophysics with dark matter, dark energy and black holes last week to as simple as possible for keen readers.
It is intended especially for aspiring secondary level students and readers interested in this as a highly specialised academic field studied in electronics engineering and physics in tertiary institutions in PNG and abroad.
Everyday life from in dwelling place, office, a shop or garden or out fishing, you have a plan of action. That can be thought out mentally because you know exactly what you are going to do for the day for whatever result it may be.
In carrying out that plan, it is now a practical event that you have to perform. While performing that job or act, you do so many things like avoiding dangers, solving problems, taking steps to maximise the result of your task, trying to produce the best result in less time and so on.
If in rare occasions when mistakes happen, whether deliberate or not it will cost you something in a mild penalty or a severe cost.

Types of modulations for radio transmission. – Picture from watelelectronics.com

The activity described above is work done on a bigger scale. In the case of this lecture, it can be referred to as activities based on a macroscopic scale. The much smaller scale of the description of such activities as described above is called a microscopic phenomenon or work done on a microscopic level.
We are saying small because there is a hint there already in the use of the word which forms the subject of today’s lecture and this is the word electrodynamics. It is quite a big term but when we break it up it will become easier for us to understand.
‘Electro’ comes from the word electric and electric or electricity is to do with electrons. In our previous lectures we have used this word to mean those which carry negative charges and you are well aware of it. Conversely those which carry positive charges were protons and likewise those particles which do not carry any charges are known as neutrons.
Now dynamics is the next term which we have discussed earlier as well and those were the movements that were created as a result of the changes undergone by those particles.
Consequently, we have the effects most extensively studied in this field around the world such as the charges, magnetism, electromagnetism, electromagnetic radiation, nanoparticles, electromagnetic induction and magnetic dipole whereby a magnetic force can be exerted on an electric charge that is moving as depicted in a magnet. Thus, the keyword here is movement. So now when we can combine the term electrodynamics, we mean the movement of the negatively charged particles and the changes that go with it.
The World’s Encyclopedia defines electrodynamics as “study of phenomena associated with charged bodies in motion and varying electric and magnetic fields since a moving charge produces a magnetic field.
Electrodynamics is concerned with effects such as magnetism, electromagnetic radiation, and electromagnetic induction.”
For the purpose of our discussion, we could say that the movement of electrons along a pathway carries a negative charge.
As a result of that charge which are the moving electrons, it creates a magnetic field with it which also affects the electrons in turn. Here we can see that we have two fields and one is an electric field and the other is the magnetic field. Both operate with each other to result in the electricity, magnetism, electromagnetism, electromagnetic radiation and electromagnetic induction applications.

Technology as a working field of electrodynamics
Some could argue that electrodynamics and technology are inextricably linked to each other. Of course, they are. An example is a message sent from a space received here on earth or vice versa.
Likewise, information is sent from the earth like our very own information centre of the National and Supreme Court facility in Waigani as this department employs this very advanced technology with the communication satellite and its links for relay of court matters and judicial information.
Upon reception, the satellite relays this information to whatever centre it requires, whether it be an isolated location in a province or anywhere in the world to those who are indexed to the to the National Court’s bands and frequency.
The information transmission and reception here is beyond the limits of the atmosphere of the earth that can cause mishaps and further to that limit its reachability capability.
The reason being that the information is transmitted and received above the influence of the earth’s atmosphere. Whilst saying this, credit must be accorded to the National and Supreme Court for the innovation. It is the PNG’s final hope and survival. This is the nation’s oasis that roots out any evil in corrupt practices which stalls the progress and well-being of the citizens. The National Court management is taking this lead in PNG in technology to avail justice to the powerless and all must applaud what the National and Supreme Court Management has accomplished for the rule of law’s rampancy.
We have just described an information transmission through a medium of electromagnetic radiation.
That radiation was a radio wave that could use the two phenomena of electric charge to generate a current and induces a magnetic field that allows it to travel at the seed that goes around the planet earth seven and half times in one second. How incredible is that!
The above method of information relay did not require a medium to do so because it is self-propagating. That very nature of the dynamics gives the magnitude of the speed of light that British physicist James Clerk Maxwell first worked out earlier on in his Maxwellian equations. Here, it can be seen that with Albert Einstein’s Special Relativity, the electromagnetic radiation as described above does not need a medium to travel on.
Therefore, electromagnetic radiation as a wave can travel in a vacuum unlike the other waves. So, electrodynamics in such a scenario has so many uses that can be derived with its workability as we will further discover in the following discussions. Application and emerging potentials of electrodynamics in technology
The applications are quite vast. One is the transmission of information in the electronic medium such as the one described above. The electronic medium of communication can come in the form of texts, audio, animations and videos.
Further applications are in the ignition of motors. Those are know as the electromagnetic inductions whereby a small current through a transistor can cause a huge blast of a temperature that can keep a whole engine’s pistons to send all cylinders firing.
Further to that we have electromagnetism whereby a small relay circuit is built to magnetise a pivotal metal known as an armature to close and open a circuit when it is magnetised and demagnetised respectively. You have heard of automatic controls and this is a most common method used.
The other use is known as electromagnetic radiation. This is very important in particularly the radiation that come from the sun as well as other bodies and particles.
As we said in our last lecture last week that the sunlight, we get to make vitamin D in our bodies and the plants also take sunlight to make the simple sugars called glucose in a chemical process called photosynthesis.
There are also other components of the electromagnetic radiations that become very important in the modern life. These are the other parts of the electromagnetic radiations such as the infra radiation and radio waves. These waves are used to send messages in the form of digital encodings by way of modulations. A carrier wave is incorporated with a sound wave. For reception, the carrier wave is demodulated to retrieve the actual message spoken on the other side.
The actual method of modulation could by the frequency modulation known as FM or amplitude modulation know as AM. Hence, the device to get the message could be in the form of an FM radio or an AM radio. So, the message you receive on your radio and television are basically from these segments of the electromagnetic radiations.
There are studies under way into exploring the dark matter and dark energy as well as the black holes as we also looked at last week. These are undiscovered areas of the astrophysics and the electrodynamics play an important role.
Black holes cannot be detected with magnetic deflections from satellites to give us more insight. However, their effects on other matter can be studied. Concerning dark matter and dark energy, this is what Wikipedia says;: “In short, dark matter slows down the expansion of the universe, while dark energy speeds it up. Dark matter works like an attractive force — a kind of cosmic cement that holds our universe together. “
This is because dark matter does interact with gravity, but it doesn’t reflect, absorb, or emit light.
Absorbing and emitting light quickly reminds us of Albert Einstein’s “Photoelectric Effect” of the energy packet called the quanta. An extension is that any particle is in fact capable of absorbing and emitting light. A study which leads into laser technology which can emit after light is amplified and simulated to emit radiations. This also opens up more corridors into a huge energy realm that has more energy to enableman to send missions away from the planetary missions.
My prayer for us today is “Let us take everything to God in prayer.”
Next week: Plasma physics in technology

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