Light in science and technology


GOOD day everyone. Our seventh lecture on the Science in Action Series is on light. A warmest welcome to you all.
As you may know, from the outset that without light there would be complete darkness. Now when we see the term light we automatically think of the opposite as darkness. Well on a common understanding it is but in the science of physics it is not, because it includes the other extremes as the radiations of the electromagnetism and they are also known as light. These are all revealed in this lecture.
We also know that light is the principle catalyst that enables plant photosynthesis and this produces the simple sugar called glucose in the overall carbohydrate equation. This gives rise to life as the supplier of energy in the hydrocarbons in both organic and a decayed repository as fossil fuels to move all plants and animals in biochemical and biophysical reactions as well as moving all artificial machinery and automobiles on planet earth to do meaningful work.
In physics (science), light is a form of energy. It is found in a form known as an electromagnetic spectrum. A spectrum is an arrangement of the parts. Therefore, electromagnetic spectrum is the arrangement of the parts of an electromagnetic spectrum. Light with the present form as we know has been identified by many scientists in the past called physicists.
The arrangement of the electromagnetic spectrum is based on the wavelength and magnitude or size of each part. Each part are basically composed of levels of energies that are able to travel or radiate. Starting from the first wave with a very long wavelength and less energy to the one wave with a very short wave length is called a radio wave, followed by microwave, infrared, visible light, ultraviolet ray, X-ray and the gamma ray with the very short wave length in nanometers and its frequency in terahertz.
The term light is used in science and physics to mean all the rays in the electromagnetic spectrum listed above although light can be used to mean the visible light that our eyes are able to see.

Light sources
Lights come from a lot of sources. The principle form of light is from the sun. Both in the past and present light comes from campfires and kerosene lamps. Light can also come from living things like animal and insects like fireflies called bio-luminescence. Light in the current age come from electric lights. Light can also come from light emitting diodes.
Lights that are phosphorescent come from excitation of atoms and molecules and emit light when they reach a higher energy level and when they fall or recede emit then they emit those lights. Such lights are used in cathode ray tubes in old TV monitors as well as computer monitors. Lights are also emitted by fluorescence. When high powered energy rays hit objects, they emit lights.
Lights can also be produced as a disturbance by a boat when it travels through a sea of the microscopic plants called phytoplankton that float and occupy huge areas on the surface of the sea and photosynthesise.
The human eye only detects visible light wavelengths. It cannot detect the other wavelengths like the infra radiation because the wave particle that forms the energy called the photon does not have enough energy to cause the excitation or raise energy level that will last to raise the visual molecule retinal in the retina of the eye. The visual molecule retinal switches on the visual sensation for the brain to form the image for the eye to see.

Snakes however, can detect infra radiation rays through their cellular water that gets heated by this ray. After being heated a thermal imaging is done to sense the presence of the infra radiated ray. The heat is used as a signal that activates the heating effect.
Also, the eye cannot see in the high energy ultraviolet ray as well because they are absorbed by the cornea of the eye. The rods and the cones in the retina of the eye cannot detect very short wavelength of radiation in such magnitudes of nanometers (nm).
Other animals such as insects and crustaceans like shrimps do not have eye lenses unlike other animals like humans. Those animals can detect ultraviolet radiations by quantum photo absorption similar to the methods used by humans to detect visible light.
It is reported that children and young adults can detect ultraviolet radiations in a reduced nanometer wavelength of a range from 310-313nm.
Light is studied in a field called optics. Light has a constant speed of size 3 x 108 meters per second. This is like it saying light can travel around the world seven and a half times in one second. Light as an electromagnetic radiation has a magnetic effect as well as an electric effect. Because of this character, light generates and propagates on its own to travel. It has a rate of two vacuum constants called permittivity and permeability that is to initiate itself and propagate or travel very fast (at 3×108 ms-1). The permeability measures the rate of not allowing electric lines and permeability measures the allowance of magnetic lines. These two phenomena allow for light to self-initiate and propagate or travel out in all directions like a wave and a particle in a way called wave-particle duality just like any other electromagnetic energy quanta of photons. It can travel through a vacuum unlike sound. Sounds can travel only through mediums like through solid, liquids and gases while light cannot require medium to travel.]

Light can bend
Lights can bend and this is called refraction. When light passes from a medium of a lesser density to a medium of more density it bends towards the normal. If it travels from a denser object to a less, denser object, it bends away from the normal. This results from a ray of light incident on an object whose incidence is not normal or orthogonal results in a change in the direction of the beam. For measurement, this phenomenon is given in the Snell’s law.
The range of applications of light in communication in light emitting diode and communicationis very huge. Further in the computing industry, the discovery of the new form of light involving polaritons is a potential area to contribute to quantum computing.
Use of fibre optics with use of different refractive indexes of the glass strain for total internal reflection enhances communication in today’s world.
My prayer for PNG today is in chorus: “Because He lives, I can face tomorrow. Because He lives, all fear is gone. Because I know, yes I know, He holds my future and life is worth the living just because He lives.”
Next week: Sciences of the Lenses and Technology

  • Michael Uglo is the author of the science textbook “Science in PNG, Pacific, Asia and Caribbean, and a lecturer in avionics, auto-piloting and aircraft engineering. Please send comments to: [email protected]