Photoelectric effect of physics in technology


I WAS working with the Curriculum Development and Assessment Division (CDAD) of the National Department of Education (NDOE) for a three-year stint.
In the year 2001, as the Science and Technology Section head with the Secondary and National High Schools level at CDAD, I completed a Grade 12 Physics teachers’ resource unit booklet titled Energy Transmission by Waves started off by the previous incumbent namely Russel Jackson who was a physics graduate from the Oxford University, England. This resource booklet is currently in use by the Grade 12 Physics teachers to teach the Unit 4 Physics topic on Waves and Energy Transmission in PNG secondary and national high schools at the moment. I hope they still do.
Whilst on energy transmission by particles, another particle I have encountered at CDAD was a nitrile ion. It is a triple bond radical with a carbon ion which are attached in a triple bond and carries a negative charge thus it is called an anion. Before chemistry big names and the PNG Grade 12 Chemistry co-examination panel like Professor Frank Griffin – UPNG, Dr. Wimblemann from Germany – UOG, Dr Charles from England – Unitech, Dr Peter Petsul – UPNG, Freddy Kuama – UPNG, Arron Hayes from Australia – NDOE, I discussed nitrile ion as a functional group that allows for formation of a fibre molecule and the other for a protein molecule synthesis.
Fortunately, my explanation was accepted and the question on the organic chemistry was included in the Grade 12 examination in that year. The idea exemplified here is that fibre from for instance plant cellulose can be made into clothes that you wear.
Quite contrarily, a protein is something that you can have as food whether it is a plant or an animal protein. This particular particle (nitrile) has carried an imminent potential to create such wonders that can also convert into energy as proteins can convert to saccharides and cellulose are polysaccharides just like the wave particle that transmit energy that both can, do work on the other side of the equation.
That was a preamble to this lecture. The photoelectric effect is a demonstration of this energy coupled with its transmission in the form of a wave as an energy particle. An energy packet called a photon (Ephoton) gives rise to the speed of light(v) as a factor of the Planck’s constant and together divided by the photon wavelength. A constant is a number that is always given in any mathematical or chemical equation. (That is; Ephoton=hv=hc/wavelength of photon.) The maximum amount of energy is required in electron volt (eV) to displace a valence electron from its rightful position. The two as a wave and a particle to effect in the energy and its transmission are inseparable which has brought to the revolutionizing phenomenon of the wave-particle duality as Albert Einstein found and established for the contemporary physics studied throughout the world.
This is a Nobel Prize winning attempt by Albert Einstein who brought to light the concept of electron displacement from selected surfaces of metallic substances. When a beam of light is passed to a surface essentially valence electrons are displaced as we have seen earlier in previous lectures. In the previous lectures we have also seen that electrons in the outer layers of a nucleus of a selected metallic substance which are called valence electrons can easily be displaced. Those valence electrons carry less, binding energies versus the other preceding electrons progressively lying closer to the nucleus who are progressively more strongly bounded to the nucleus in a linear relationship.
That is directly proportional to the nucleus which means the closer the electrons are to the nucleus the more energy they carry. In other words, the closer they are to the nucleus, the more working energy they have. Hence electrons closer to the nucleus are harder to remove than they outer lying valence electrons.
The phenomenon of the photoelectric effect is simply light rays whose energy are greater than the binding energy inherent to the valence electron(s) are displaced. Therefore, those displaced electrons are the freed electrons now driven to the conduction band to allow for them to flow resulting in the flow of electricity that is literally flow of electrons in one way and the flow of current in the reverse direction.

Applications of photoelectric effect in technology
The dislodged electron called the photo electron acquires its energy from its frequency from this field of study. It is not the intensity of the light as one may anticipate. For instance, you can increase the intensity of light and expect to energise the level of energy of the photo electron which does not work. Only an increase in the frequency than intensity will intensify the content energy of the irradiated photo electron from an energy packet called the photon that hit the metallic surface in the form of a wave-particle duality.
The applications are such as the exact tracing and detection of electron emissions of surfaces effecting photoelectric emission.
Such examples will be the beta energy waves seen in medical devices to scanning patients of, for instance, babies in the pregnant mothers. Other areas will be in vascular tissues such as arteries for correct fluid dynamics as well as scanning of delicate and subtle organs such as brains and eyeballs.
Also, a huge application is in the electronic devices whereby every electron can be accounted for such as Geiger Muller Counter for detection of radiations as alpha, beta and gamma particles. A crucial determination can be made of such as the critical points for a cut off point for a saturation or an allowable electron quantum for an amplification of a transistor. Furthermore, an electron is determined for a transistor to act as a switch for a message relay from one electronic device such as an emitter and collector currents from a biased base current say like 0.6 amperes to run a load such as a loudspeaker or a light (lamp) for message delivery in electronics.
Other applications are seen in photocells. The photocells have two ends called electrodes. One end is the anode and the other is the cathode. When light is incident on the cathode it emits electrons which are attracted by the anode. This will switch on a separate switch so it can thus act as a relay. That relay could be a doorbell or a security light system.
There are also other applications like the famous solar cells. It is a specially prepared solar cells made of the element silicon. Silicon with a four-valence electron makes a good option to induce electrons in photoelectric emission as the energy packet of the photon. The four
valence electrons flow as current as they get excited and freed from their joules of the working energy. This has been a profound scientific leap taken from modern physics resulting from the whole concept of the wave-particle duality of the quantum mechanics.

Arriving technology with photoelectric effect
There is currently an exciting finding in the area of the photoelectric effect in quantum mechanics and particularly quantum mechanical interference. This is a quote from David Busto, a doctoral student of Atomic Physics at Lund University (LTH) in Sweden: “Now that we understand there is an asymmetry in the free electrons’ movement, we can gain a better understanding of the quantum dynamics in photo-ionisation.”
Busto further said, “When we change the direction of the electron wave, we are using quantum mechanical interference. That is, the electron takes several paths towards its changed waveform. In classical physics, the electron can only go one way.”
The potential inherent here is that behaviour of electrons can be manipulated in atoms and molecules given their asymmetrical natures of the movement pattern. That displayed a controversial view to the classical physics that hosted the thought that the movement of the electrons has been standard and a routine trajectory. Molecules and atoms can be subjected to be controlled to suit one’s need for any application at all.
Such can open up new applications in nanotechnologies and nanocomputing when the current silicon wafer technology is nearing its 10 atomic diameter mark of a 100 micro-meter. Aggravating the current technology and a sigh of relief is the excessive build-up of heat that limits the power of computational expansion.
In addendum, there is a mammoth need for reliability, customisation and robustness of the zettabyte in a trillion gigabytes of information circumventing and clogging the planet earth as I am speaking.
My prayer for PNG is in this hymn (as singing is praying twice): “Trust in the Lord and you shall not tire, bless Him the Lord, you shall not weaken, for the Lord’s own strength will uphold you. You shall renew, your life and live”

Michael John Uglo is a lecturer in in Avionics, Auto-Piloting and Aircraft Engineering. Please send your comments to: