1. Molecular structure

To understand what atomic energy is one must first have a correct knowledge of the structure of the atom.

Before the time radium was discovered, atoms were considered to be indivisible units of matter. The picture of the structure of the atom is known to have changed with the development of physics. Originally the atom was thought of as something like an extremely small ball. We know it to be very simple or very complicated (сложный) depending on the chemical element.

In general every atom consists of a miniature planetary system with a central nucleus or "sun", around which one or more small particles or planets revolve constantly. This is like our solar system. The nucleus of each atom contains one or more particles called protons, each proton having a definite positive electrical charge. The little bodies circling around the nucleus of each atom vary in the different chemical elements.

Similarly, the number of positive protons in the nucleus is different in each chemical element.

The neutron has a similar mass very close to that of the proton, but carries no charge.

The combination of protons and neutrons with planetary electrons is a basic building pattern which we can find in all substances.

2. Application of the electric current

It is almost impossible today to find any technical development which does not use any action of the electric current. More and more the application of the electric current makes our work easier and accomplishes a given task more efficiently.

The old kind of a doorbell used the small amount of power delivered from one dry cell; the switch which is closed when the button is pressed permits current from the dry cell to flow through the magnets of the bell and so attracts the iron armature to make the bell ring. The power and forces involved are small, and the distance covered by the electric circuit is usually measured in feet.

In the ordinary electric light the current is made to flow through a wire and to heat it to incandescence. No mechanical forces are utilized in this case. When passing through the wire, the current agitates the molecules of the wire to such an extent that they send off electromagnetic waves which we call light.

The action of the current in this case is known to heat the wire: the power used in these lighting devices is measured in millions of horsepower.

In the case of radio device current is made to flow to-and-fro in a vertical wire (the transmitting antenna) about a million times per second. The strength of this current is made to increase or decrease in accordance with the voice of speaker. In another vertical wire (the receiving antenna) which is hundreds or perhaps thousands of miles away currents are set up and if properly amplified, give off a reproduction of the voice, sent by the transmitting antenna.

The power is radiated from the transmitting antenna in the same way as heat and light are radiated from the sun; such radiated energy not only requires no connecting wires for its trans-mission, but actually travels better through a vacuum than it does through the air.