Part 10 (2/2)
Caution must be used to prevent the different coils or turns fro each other When completed, the coil may be immersed in water, the current turned on, and left so until the water is sufficiently heated
[Illustration: _Figs 97-98_ RESISTANCE DEVICE]
HOW TO ARRANGE FOR QUANtitY OF CURRENT USED--It is difficult to deterth the coil should be, or the sizes of the wire, unless you knohat kind of current you have Youup your own apparatus for the purpose ofa base of wood (A) 8 inches long, 3 inches wide and 1 inch thick On this mount four electric lamp sockets (B) Then connect the inlet wire (C) by means of short pieces of wire (D) with all the sockets on one side The outlet wire (E) should then be connected up with the other sides of the sockets by the short wires (F) If, noe have one 16-candlepower lah the wires (C, F) If there are two lamps on the board you will have 1 ampere, and so on By thisand it will also afford you aout whether you have too much or too little wire in your coil to do the work
[Illustration: _Fig 99_ PLAN VIEW OF ELECTRIC IRON]
AN ELECTRIC IRON--An electric iron is made in the same way The upper side of a flatiron has a circular or oval depression (A) cast therein, and a spool of slate (B) is h resistance wire (C) is wound around this spool, and insulating material, such as asbestos, must be used to pack around it Centrally, the slate spool has an upwardly projecting circular extension (D) which passes through the cap or cover (E) of the iron The wires of the resistance coil are then brought through this circular extension and are connected up with the source of electrical supply Wires are now sold for this purpose, which are adapted to withstand an intense heat
[Illustration: _Fig 100_ SECTION OF ELECTRIC IRON]
The foregoing exah resistance wires, has a very wide application, and any boy, with these examples before him, can readilybeen the dream of scientists to convert heat directly into electricity The present practice is to use a boiler to generate steaine to provide the motion, and a dynamo to convert that motion into electricity The result is that there is loss in the process of converting the fuel heat into steae the steam into motion, and loss towater-power there is less actual loss; but water-power is not available everywhere
CONVERTING HEAT DIRECTLY INTO ELECTRICITY--Heata boiler, an engine or a dynamo, but it has not been successful fro, however, to know and understand the subject, and for that reason it is explained herein
METALS; ELECTRIC POSITIVE-NEGATIVE--To understand the principle, it ative to each other You will remember that it has hereinbefore been stated that if, for instance, iron and copper are put into an acid solution, a current will be created or generated thereby So with zinc and copper, the usual primary battery elements In all such cases an electrolyte is used
Ther is used but the metallic elements and heat The word thermo means heat If, noe can select two strips of different metals, and place theative relations with each other, and unite the end of one with one end of other by means of a rivet, and then heat the riveted ends, a current will be generated in the strips If, for instance, we use an iron in conjunction with a copper strip, the current will flow from the copper to the iron, because copper is positive to iron, and iron negative to copper It is froative is taken
The two metals most available, which are thus farthest apart in the scale of positive-negative relation, are bis 101_ THERMO-ELECTRIC COUPLE]
In Fig 101 is shown a therether, with thin outer ends connected by alvano means is placed in this circuit A lamp is placed below the joined ends
THERMO-ELECTRIC COUPLES--Any nuether and joined at each end to a coe flow of current obtained thereby
One thingas there exists a difference in temperature between the inner and the outer ends of the bars (A, B) Thisest itself
CHAPTER XV
ALTERNATING CURRENTS, CHOKING COILS, TRANSFORMERS, CONVERTERS AND RECTIFIERS
DIRECT CURRENT--When a current of electricity is generated by a cell, it is assu the wire in one direction, in a steady, continuous flow, and is called a _direct_ current This direct current is a natural one if generated by a cell
ALTERNATING CURRENT--On the other hand, the natural current generated by a dyna in its character--that is, it is not a direct, steady flow in one direction, but, instead, it flows for an instant in one direction, then in the other direction, and so on
A direct-current dynamo such as we have shown in Chapter IV, is much easier to explain, hence it is illustrated to show the thirdan electric current
It is a difficultcurrent , in a measure, too technical for the purposes of this book, but it is important to know the fundamentals involved, so that the operation and uses of certain apparatus, like the choking coil, transformers, rectifiers and converters, may be explained
THE MAGNETIC FIELD--It has been stated that when a wire passes through the net, so as to cut the lines of force flowing out froe of electricity
[Illustration: _Fig 102_ CUTTING A MAGNETIC FIELD]