Fred Fries, age 14, of Bayside, N. Y., for his question:
What is electromagnetism?
The philospher scientists of the Middle Ages were rather muddled thinkers. The more practical scholars of the 17th century accepted only facts which could be proved which is the scientific approach, But some of them went too far and refused to believe a fact unless they could make a model of it, These lopsided thinkers could have never understood electromagnetism.
In science, there are many proven facts which are beyond the range of our senses. We cannot see, hear, touch or smell electromagnetism. But we can study what it does and use this indirect information to prove it exists and fathom its nature. This is like a math problem in which we use a number of known items to find the value of X, an unknown item.
Electromagnetism was outlined in 1860 by James Clark Maxwell. Scientists knew about white light, infrared and ultraviolet light. They knew of a relationship between electricity and magnetism and used this knowledge to make dynamos. Maxwell saw a relationship between all these forms of energy. He used them as the known facts pointing to an X factor in an equation. He predicted that these and other forms of energy were different aspects of one great force.
Maxwell’s X was electromagnetism. White light, infrared and ultraviolet, radio and radar, X rays and gamma rays are all forms of electromagnetic energy in action, As its names suggests, it is a sort of marriage between the forces of electricity and magnetism. On a small scale, it exists in the energy field which surrounds an electric current, On a cosmic scale, it is the radiant energy of the sun.
Electromagnetism is a dynamic force stronger than gravitation. But it is much weaker than the nuclear energy released from the heart of the atom. It travels at the speed of light, which is about 186,300 miles a second. It fans out in straight lines from its source and pulses along in a vast assortment of different wave lengths.
The electromagnetic spectrum is a wide band of assorted wave lengths ranging from very short to very long. White light occupies a narrow strip in this spectrum. Longer wave lengths reveal themselves as infrared and radio. Shorter wave lengths reveal themselves as ultraviolet and X rays.
The kilometer' which is almost a mile, is used to measure the longer wave lengths of electromagnetic energy. The shortest are measured by the Angston unit and there are one hundred million of these units in a centimeter. The wave lengths of white light ranges from about 3,800 to 7,800 Angstroms, which is a very narrow strip on the electromagnetic spectrum.