Show why your radio tubes need filament light the fact that eliat a radio bulb does emit light Is entirely an incidental feature of its operation what is desired tit in a tube Is a flow of little particles of electricity called electrons and the easiest way to obtain it Is to burn certain kinds 0 of wires tit in glass bulbs from which the air lim been aisch exhausted the temperature must be quite high in order to inako the flow copious tind and most wires must mun be heated white hot by the current front from the A battery for proper operation of course the incandescent wire or il lament as aa it is correctly called emits considerable light but this phenomenon tins has absolutely no connection with the functioning ti of the tube from the radio standpoint it is quite possible to obtain a stream of the minute electrons in a tube by the use of certain substances known ns as radioactive hut but their expense and rarity make their practical application extremely limited radium and radium compounds are foremost in ahn radioactive group so the cost of tubes equipped equip pod ath ith filaments of tills this precious element clement can vastly easily ho be imagined no A battery incidentally would bo be required for such buch tubes as the he low flow or of electrons aiom radioactive compounds Is and continuous certain less expensive chemical compounds of high electron emitting properties have been successfully employed in radio tube the ilic wire which ordinarily must io ie burned nl at willae heat bent la Is e coated boated willi a lavoot one of these compounds and the tute tube la Is thou operated at a mere dull cher ry red heat in many of the modern tu tubes be of 0 both abo ali coated tind uncoated cd varieties title or no ito light Is through tile the glass because of the inner coating of mercury which lines tile bulbs the of tilla coating varies considerably as will therefore the amount of light thai chrt penetrates penetrate 9 through liro iRh it so co no cance can be att aclid to the ahe arll liance clauce of the illumination illuminat lon |