BROADCAST ENERGY

Radio Record, Volume I, Issue 16, 4 November 1927, Page 11

BROADCAST ENERGY

WONDERS OF RADIO, The energy expended by a fly crawling up a wall is about equal to that received on a wireless set turned into a 6000 station ten miles distant. To us the fly does not, appear to be very hard at work; in fact, the ease with which it defies gravity often invests us with a longing for similar powers, But the work involved in transmitting a similar amount of energy through space is hard work indeed (says Sydney ‘‘Radio’’). The process of broadcasting, like everything else, depends upon work being done. Energy is expended, and, therefore, work is done wken one speaks; work is done when the microphone converts the sound waves into electrical vibrations; work is done when the amplifying circuits build up. these vibrations, and work is still being done when these vibrations are forced ont through the ether at the rate of 186,000 miles a second. Work is done when a receiving set intercepts these radio signals and converts them into music to which we listen in comfort at home. Power of thé Voice. It is said that the energy expended by a speaker when tikking m a normal conversational tone is in the order of a few microwatts, if that energy is expressed in electrical terms. A microwatt is one-millionth of a watt, a small unit. It is possible to get an idea of how small this really is by comparing it with an ordinary incandescent electric lamp. A 25-watt lamp, for instance, will barely light 2. fairsized room. Suppose we Jivide such a lamp into twenty-five «qual little lamps of one watt each, take one of them and sce how well it lights the rooni. Imagine one of these 1l-watt lamps further divided into 1,000,000 lamps of one microwatt each, and consider to what extent one, two, a dozen, or even 19) of them, would light the room. But, if we take the energy of half a dozen of these imaginary lamps and pnt ‘£ tn a microphone in the form of sound waves, we are able to start a symphony orchestra’s concert on its almost instantaneous journey around the world. One engineer has taken a different way to show the amount of energy in the human voice, He says that if it were possible to convert this energy directly into electricity and use it for heating purposes, it would take fifty million people shouting at the top of their voice to make a cup of tea. One can easily see that the human voice is hardly a power plant. Just as a matter of interest, let us compare the energy of the voice with the power of a broadcasting station. We have said the energy of the ~oice, if converted into electrical units, ts in the order of a few icrowatts. Suppose we estimate it at five microwatts. If the output of a broadcasting station is 500 watts, the vast differetice is veadily seen. In round figures, the power of the station is 100,600,000 times greater than the voice. Or, if we are speaking of a super-power station, the difference may be around 10,060,000,000 times.