"Pulsing through our classroom walls and through your bodies at this very moment are hundreds of different forms of electromagnetic radiation! How are you feeling as a result?" This attention-grabbing statement produced mainly quizzical expressions on my students’ faces. But it also triggered fascination and an investigative frame of mind. When the electromagnetic spectrum unit was complete, I hoped it had also evoked a sense of wonder.
One of my favorite topics of study during my years as a classroom teacher was the electromagnetic spectrum. In multiple ways we are continually impacted by it. Where, then, do we begin in our explanation? The matter surrounding us is composed of elements or compounds of elements, or mixtures of elements and compounds. The smallest units of elements are atoms.
Little more than a century ago, the structure of the atom was discovered: a dense nucleus containing one, or more often, a cluster of electrically positive protons, together with electrically neutral neutrons. Surrounding the nucleus is a cloud of negatively charged electrons. In the early 1900s it was shown that most of the atom is just empty space. Different elements were composed of different numbers of protons, neutrons, and electrons.
To understand the nature of the ubiquitous radiant energy surrounding us, we must realize that all atoms possess kinetic (motion) energy at all times. All substances, therefore, possess heat. The higher their temperature, the greater their kinetic energy. Even objects from our kitchen freezers have heat: they are hundreds of degrees above absolute zero--the coldest temperature possible. Atoms may be energized further in many other ways.
As atoms move, their electrically charged particles move with them. When electrical charges move, they release packets of energy called photons. These packets behave like particles, but they also have characteristics of waves. Each instant of our lives we are constantly impacted by a flood of photons or waves, also known as electromagnetic radiation.
Light, a tiny fraction of the many hundreds of forms of electromagnetic radiation, is visible to humans. Most of the remaining forms are not detectable by our human senses. But the multitude of tasks for which they have been harnessed in our era of advanced technology challenge the imagination. In upcoming posts I will discuss more details of the importance and fascination of the electromagnetic radiation which surrounds us.
The Apostle Paul wrote of God’s creation of invisible as well as visible things. For him the invisible things were no less real: “For by Him all things were created: things in heaven and on earth, visible and invisible…” (Colossians 1:16 NIV). Scientists of the 21st century are making more and more discoveries of the reality of the invisible.