ELECTRICITY 



1986 



ELECTRICITY 



it would require twice as many atoms, since 

 there are two atoms of hydrogen in one mole- 

 cule. But atoms are not the smallest objects 

 in nature. The electron is so small that it re- 

 quires about two thousand electrons to equal 

 one hydrogen atom in weight. These extremely 

 small objects which we call electrons are the 

 source of all the interesting effects which we 

 call electrical. See ATOM; MOLECULE. 



Atoms are not electrically charged under 

 ordinary conditions, but electrons are always 

 electrically charged. Every electron, every- 

 where and always, carries an electric charge. 

 It is believed that the electron itself is the 

 electric charge. The curious thing is that 

 every electron carries exactly the same amount 

 of electric charge as every other electron. The 

 quantity of electric charge carried by every 

 electron is called the elementary electric charge. 

 It is the smallest electric charge known to exist. 

 When an electron is added to an atom the 

 atom is charged negatively. When an atom 

 which is uncharged has an electron taken away 

 from it the atom becomes positively charged. 



How the Current Flows. To understand how 

 an electric current flows through an electrical 

 conductor such as a copper wire, we must pic- 

 ture to the mind the atoms of copper of which 

 the wire is composed, with the inevitable 

 spaces between them. If a flask were made of 

 copper and tightly closed and then placed un- 

 der very great pressure, water could be made 

 to pass through the sides of the flask before 

 the flask was broken, showing that there are 

 spaces between the atoms of copper through 

 which water can pass. No matter how com- 

 pact a substance may appear, there are spaces 

 between the atoms of which it is composed. 

 If we imagine the atoms of the copper wire 

 with spaces between them and electrons, much 

 smaller than the atoms, moving freely from 

 atom to atom, we have a picture of what goes 

 on in a copper wire when it carries an electric 

 current. The current in the wire consists of 

 electrons passing from atom to atom through- 

 out the length of the wire somewhat as a 

 water bucket is passed from hand to hand in a 

 bucket brigade. The atoms are set in more 

 rapid vibration by the motion of the electrons. 

 In this manner the current heats the wire, for 

 the vibration of the atoms constitutes heat. 



To understand electrical action in space it is 

 necessary to understand what is meant by the 

 ether. Let Us use an illustration to make this 

 clear. If an incandescent electric light bulb 

 is broken there is a loud report as the air 



rushes in to fill the space. The air had been 

 pumped out of the bulb until only about one- 

 millionth part of the air which was at first 

 in it remained. Practically all the air was re- 

 moved, yet eomething remained in the bulb 

 which was able to transmit the light across 

 the space between the white hot filament and 

 the glass. This something is called the ether. 

 Ether fills all space not occupied by material 

 objects. Ether transmits the Jight of the sun 

 through space; it fills the spaces between the 

 atoms of every substance; it can be caused to 

 vibrate in a certain way by an electrical dis- 

 turbance, and such vibrations travel through 

 the ether in the form of waves. These waves, 

 if they are short enough, from about 1/30,000 

 to about 1/50,000 of an inch in length, consti- 

 tute light, and affect our eyes; if they are 

 longer, our eyes are not affected by them. We 

 call the longer waves in ether electric waves, or, 

 more accurately, electromagnetic waves, and 

 make use of them in wireless telegraphy. A 

 special receiver is made which is sensitive to 

 the longer waves. The human eye is a sensi- 

 tive receiver for the shorter waves. 



Velocity. Electrons by their motion set up 

 waves in the ether. These waves travel 

 through space with a speed of about 186,000 

 miles per second. The waves set up by the 

 electrons may be of the longer kind used in 

 wireless telegraphy, or they may be of the 

 shorter kind known as light. When an elec- 

 tric current is flowing along a wire such waves" 

 are set up all around the wire by the motion 

 of the electrons in the wire, and these waves 

 follow the course of the wire. The waves in 

 the space around the wire transmit the power 

 of the electric current. 



In an insulator, such as glass, the electrons 

 cannot move easily from atom to atom. When 

 they do move through an insulator as through 

 air they do so with great violence. In an in- 

 sulator the electrons are bound to the atoms; 

 hence, under ordinary conditions no current 

 can flow through an insulator. 



When an electric current flows in a coil of 

 wire the coil acts in all respects like a magnet. 

 The current flows around the coil in nearly 

 complete curies. An electric current flowing 

 in a circle has magnetic poles, one face of the 

 circle being a north pole and the other face a 

 south jDole. It is believed that in a magnetic 

 substance such as iron the electrons move in 

 circles around the atoms. Each atom with an 

 electron circling about it has a north pole and 

 a south pole. 



