you'll notice by the way that the direction of electron flow is contrary to the orthodox concept of current law from plus to minus now at this point you may ask if an electronic tube is basically just a form of switch why is electronics hailed today the technique of a new engineering era to answer that question let's review six of the basic things that we can do with this new kind of switch in the first place we can rectify current with converting a we can do this merely by connecting an electronic tube in series with an ac circu drowned we have here what amounts to a one way street we can visualize the result of the tubes rectifying action with the the one on the left shows alternating current coming in the one on the right shows pulse lighting direct current going out the applications of this basic rectifying principle are many and important is one of them changing ac to d c on the nation's electrified ran here's another rectification for electroplating operations of all kinds of operations possible only with direct current bill another example furnishing d c and steel mills for the driving a variable speed motors such as the one controlling this giant ladle or the ones driving steel conveyors with such precise control of speed that danger of buckling and tearing and consequent mill damage is eliminated development changes vast quantities of ac to d c with higher efficiency than any similar type of conversion equipment today it's the main source of current supply for the nation's great aluminum industry an industry that has achieved a miraculous expansion to meet the demands field of these wires each particle of dirt receives a positive electrostatic char in this way air is clean thoroughly the dirt particles down to a quarter million seventy remover this is a vital advantage today not only in homes and public buildings but in industrial plants of all kinds for instance in plants manufacturing delicate instrument where air cleanliness is necessary for precision work in work rooms where optical systems are assembled for a host of military purposes and inspection rooms where my new parts must be closely examined under high magnification plane thousand feet above the earth the camera shutter opens and closes scores of square miles of enemy territory have been squeezed down into an image on a photographic plate an image measured in inches instead of miles on this perhaps out of a faint radio signal from halfway around the world now let's see what happens every time a negative but potential is impressed on the grid even though it be very minute it has a large effect in reducing the number of the negatively charged electrons which would otherwise keep line from cathode to annul conversely when the they amplifying property of the three element electronic to is put to work in a numerable way westinghouse electronic amplification now helps provide radio and radio telephone contact between airplanes and controls nations on the ground between ships and their communication bases both of them with your between individual tanks and their tank force commanders between firing line and headquarters between the drone life the night flying pilots who can turn them on by radio signal in the field of power engineering electronic amplification permits the measurement and analysis of minute voltages stepping them up to the point where they can be seen and interpreted on a telescope when this giant rotor is completed its precise dynamic balancing will be made possible by amplifying to testing of these propellers with vibration fatigue will also be facilitated by electronic amplifying due up to now we've considered two of the basic things that the electronic shown here the system then becomes capable of changing direct current into alternating current not that what we're doing in this case is amplifying in the usual way and then feeding back to the grid part of the amplified voltage continued reputation of this feedback result cumulatively in a strong alternating current  tronic means of generating alternating current is important because it can produce very high frequency frequencies up to millions of cycles far beyond the range of ordinary rotating equipment time a radio transmitter was used for large scale public entertainment at his station katie kay of the westinghouse electric and manufacturing company we are about to begin the reading of the presidential election returns between warren plea here is a new less familiar application of electronic high frequency generation i frequently heating of two hundred thousand cycles per second is now used to float him as the final step in the electrolytic plating of steel stri grip is raised to the top of the heater unit housing inside of which is a series of high frequency coils as the strip comes down through these coils induced electric current causes heat which blows the pan almost instantaneously greatly improving its struct and these are the two the generate the high frequency current which makes the entire process possible another important result of this new westinghouse electronic process is time saving tin can now be flowed at the rate of more than a thousand feet a minute reduced dielectric heating also cures intricate plastic forms faster and better hero dialectically plastic pieces being given a stress analysis carrier current relaying also applies the electronic principle of high frequency generation here's part of the equipment that does the work as equipment makes possible an enormous increase in the speed with which transmission lines can be cleared of its effect is  increase the load carrying ability of the system up to fifty percent or more with now illustrated three of the basic ways that the electronic tube can be put to work it rectifies it amplifies it generates and here's a fourth thing it circuit in but your way that it becomes a function of temperature speed time or any other variable as a result grid potential is varied and the work circuit is automatically controlled spot welder without sound without direction without laying electronic control on this equipment makes and breaks contact with second timing beam welding to electronically control a result lane part today are being literally sewn together with electric current as but welding of course represents only one opportunity for electronic control automatic step less regulation of motor speed is another application without the smooth acceleration which such control makes possible delicate materials such as the capacitor windings being handled here might be broken under the shock of starting and abrupt speed changes not from still another basic thing that the electronics can do it can also serve as a bridge to transform light into electric current here is how we replace the ordinary heat activated cathode of a two element electronic tube with one made of photosensitive material light can now replace heat as the stimulator of electronics you mentioned the stronger the light the greater the electronic you mention and consequently with the aid of an amplifier the more power flowing through the work circuit this is important because it means that photo electric tubes can function as light realize until be given an almost infinite variety of jobs to do scanning the soundtrack of the talking motion picture film you're listening to right now is one of them production line without a moment's loss of working one of the most important basic things is the electronic tube going to remain the out to be less than transforming light into electric current it can also transform electric