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critical, 586, 587
defined, 282

dimensional formula of, 540
example of effect of, 283
expressed as a velocity, 541
internal, of cells, 294

measurement of, 328
joint, 293

laws of, 285, 286, 287, 288, 289
measurement of, 308

by drop of potential, 309, 310
by Wheatstone bridge, 317, 318,

319, 320, 321

of conductors in parallel, 293
of conductors in series, 286
of electrolytes, measurement of, 327
of voltmeter, 458, 459, 460, 461,

468

practical unit of, 284, 546
Siemen's unit of, 543
specific, 285, 288
temperature coefficient of, 289
variation with temperature, 285,

289

Resistance and capacity, 629
Resistance and inductance contrasted,

616
effect on alternating E. M. F.,

617
Resistance and inductance in parallel,

624

in series, 623
Resistance, inductance and capacity,

630
Resistances, arrangement of, in bridge,

315

measurable by bridge, 324
Resistance coils, 311
Resistivity, 292



INDEX



593



Resonance, 631, 632, 633, 697, 702,

706
with inductance and capacity in

parallel, 633
with inductance and capacity in

series, 632
Resonator, 694

tuning of, 697
Retentivity, 155

Reversible ratios, bridge with, 322
Reversibility of cells, 236
Revolving armature, alternators with,

641

Revolving field, alternators with, 642
Rheostat, 302, 513, 600
Right hand rule for deflection of

needle, 345
for direction of induced E. M. F.,

422

Ring transformer, 649
Ring wound armature, 566
Ring wound generator, 569
Rocker frame, 568
Rontgen rays, 678
Rotary converter, 653
Rotating coil, E. M. F. of, 552
in magnetic field, 551
production of current by, 553
Rotating field, production of, 664
Rotation of current by magnetic pole,

351

Rotation of motor, direction of, 604
Rotation of pole by current, 350
Rotor, 665
Rule for direction of field about wire

carrying current, 348
for direction of induced E. M. F.,

421, 422
for direction of motion of wire

carrying a current, 352
for deflection of needle by current,

345

for polarity of electro-magnet, 404
Salt, electrolysis of a, 224
Saturation, magnetic, 393
Schweigger's multiplier, 365

graphs, 678
Screen, magnetic, 113, 143



Second, mean solar, 9
Secondary cell, 237

elements of, 238
Seebeck's discoveries, 528
Selenium, 285

Self-excitation, methods of, 563
Self-induction, 432, 614

absolute unit of, 433

measure of, 433

practical unit of, 433, 434
Semicircular variation, 183
Sensitiveness of relay, 705

of telephone, 705

Separation of induced charges, 32
Series, thermo-electric, 528
Series generator, 563, 582

characteristic of, 585
Series grouping of cells, 335, 337
Series motor, 602

speed of, 603

Series motor for A. C., 659
Shape of electro-magnets, 407
Shell transformer, 649
Shells, magnetic, 369
Shifting of brushes, 570, 571, 598
Short circuit, 306
Shunt, ammeter, 465, 466

defined, 293

division of current by, 301

galvanometer, need of, 380

millivoltmeter, 475

switchboard, 466

universal, 381
Shunt generator, 563, 582, 587

characteristic, 587
Shunt motor, 599

control of speed, 600
Siberian oval, 170
Siemens, 543
Siemens' electro-dynamometer, 383

unit of resistance, 543
Silicon as detector, 705
Simple cell, 193

chemical action in, 195

dissociation theory applied to, 279
Sine galvanometer, 376
Sine law, 147
Single phase alternators, 640, 644



594



INDEX.



Single phase current, rectification of,

655

Slide wire bridge, 325
Slip rings, 642
Smashing point of incandescent lamp,

511
Solenoid, 385

effect of core on field, 390

equivalent to bar magnet, 386

intensity of field on axis, 387

variation of field with current, 389
Solution, magnetization favored by,

159

Solution tension, 278
Sounder, 412, 704
Spark plug, 438
Sparking, 572
Specific reluctance, 400
Specific resistance, 285, 288
Speed of series motor, 603

of shunt motor, 600
Spheres, two coalescing, 82

two united, 81
Spider, 565
Split ring, 556, 567
Standard cell, Clark's, 212

need of, 211

Weston's, 213
Standard wave length, 706
Star development of drum winding,

577

Star grouping, 647
Starting box, 601
Static transformer, 649, 656
Stator, 665

Storage battery, charging, 245, 246,
415, 582

charging from A. C., 655

defined, 237

Edison, 250

advantages, 253
charging, 252
reactions of, 251

uses of, 254

Storage battery plates, dimensions,
242

grouping of, 243

preparation of, 239



Storms, magnetic, 180
Strength of magnets, 125, 406
Sturgeon, 403
Substances, magnetic, 121

subject to electrolysis, 221
Surface density of charge, 41, 65, 66
Suspended coil galvanometer, 378
Switch, overload, 414

underload, 414, 582
Switchboards, 579, 580
Switchboard shunt, 465, 466
Symmer's theory of electricity, 27
Synchronous converter, 653
Synchronous motor, 660

operation of, 661
Table of dimensional formulae, 547

of magnetic elements, 175

wire, 295
Tangent galvanometer, 373, 546

measurement of current by, 374

principle of, 375
Tangent law, 146
Tantalum lamp, 507
Telegraph, electric, 411

Morse, 412

Telegraph system, American, 413
Telegraphy, wireless, 698
Telephone, 440

in wireless telegraphy, 705

operation of, 442

sensitiveness of, 705
Temperature, absolute, 256
Temperature of arc, 485

variation of resistance with, 289
Temperature coefficient of resistance,

289
Tension, solution, 278

vapor, 277
Terminology of electrolysis, Faraday's,

220

Terrella, Gilbert's, 110
Theory, dissociation, applied to sim-
ple cell, 279

Theory, dissociation, of Arrhenius,
268

Grotthus', 274

of attracted disc electrometer, 102

of earth's magnetism, 181



INDEX.



595



Theory, etc. Continued.

of electrolytic dissociation, extreme
scope of, 281

of magnetism, Ewing's, 153, 395

of quadrant electrometer, 104
Theories of electricity, 27
Thermometer, platinum, 290
Thermopile, 532
Thermo-couple, 528
Thermo-electric E. M. F., 528
Thermo-electric inversion, 529
Thomson, J. J., 681, 682, 683
Thomson, Sir William, see Kelvin
Thomson effect, 531
Thomson inclined coil instruments,

471

Thomson's proof of oscillatory dis-
charge, 687

Three wire system, 581
Thunder storm, explanation proposed,

82

Time, unit of, 9
Toepler's influence machine, 49
Torsion, law of, 52, 127
Torsion balance, Coulomb's, 52, 100,

127, 132

Tractive power of magnet, 406
Transformation of D. C. and A. C.,

648
Transformer, 431, 649

auto, 652

core, 649

Faraday's ring, 431

operation of, 650

ring, 649

shell, 649

static, 649, 656

step down, 431

step up, 431
Transformers, connection of, 651

use with A. C. instruments, 472
Transmission of power, electrical, 501,

502
Transmitter, Blake, 441

wireless, 700

Tri-phase alternator, 645, 646, 647
Tri-phase delta grouping, 646

Y connection, 647



Troubles of lead batteries, 247
Tube, Crookes', 670, 671, 672, 675,

676, 677, 678, 682
focusing, 678
Geissler, 670
Tubes of force, 62
Tungsten lamp, 507, 512
Tuning of coupled circuits, 702
of receiving circuits, 706
of resonator, 697
Turning moment of magnet, 149
Ultra-violet light, 680
Underload switch, 415, 582
Unit of capacity, practical, 95
of current, 536

absolute, 355, 536, 546
practical, 228, 307, 448, 546
of E. M. F., 537

absolute, 426, 537, 546
practical, 77, 427
of electric power, absolute, 496
commercial, 496
practical, 496

of electric work, commercial, 496
of force, 11
of heat, 11, 478
of length, 7
of mass, 8
of quantity, 536
practical, 228

of resistance, absolute, 427, 546
practical, 284, 546
Siemens', 543
of self-induction, absolute, 433

practical, 433, 434
of time, 9
of work, 11
Units, absolute, 11
electro-magnetic, 535

primary, 538
electro-static, 535
fundamental, 3

Unit charge, lines of force from, 63
Unit electric field, 58, 61
Unit jars, 99
Unit magnet pole, 133
Unit quantity of electricity, 56
Universal shunt, 381



596



INDEX.



Use of electro-magnets, 408

of storage batteries, 254
Useful volts, 305
Vacua, discharge through high, 670

through moderate, 668
Value of alternating current, 612, 613
Value of electro-magnet, 405
Van't Hoff's generalization, 266

exceptions to, 267
Vapor tension, 277
Variation, magnetic, 169
Variation of magnetic elements, 176

of osmotic pressure, 263, 264, 265,
266

semicircular, 183
Vector diagram, 610
Velocity, resistance expressed as a, 541

of corpuscles, 683

of propagation of electric wave, 693,

694

Versorium, 16

Vibration, loss of magnetization facili-
tated by, 157

magnetization facilitated by, 156
Virtual amperes and volts, 612
Volt, 77, 78, 427, 537, 545, 546

denned, 307, 427, 545, 546

international, 212
Volts, lost and useful, 305

virtual, 612

Volta, 35, 186, 187, 188, 190, 191, 218
Volta's circlet of cups, 191

contact series, 187

contact theory, 188

investigations, 186
Voltaic cell, requirements of, 200
Voltaic pile, 190
Voltameter, 227

Voltmeter, 455, 458, 459, 460, 468,
470, 471, 472

connection of, 458, 459

measurement of E. M. F. by, 460,
461

reading across counter E. M. F., 595

resistance of, 458, 459, 460, 461, 468

Weston D. C., 468

Weston D. C. A. C., 470
Voltmeters classified, 462



Water, decomposition of, 218

electrolysis of, 219
Watt, 493
Watt, the, 496
Wattmeter, indicating, 499

integrating, 500

recording, 499, 500
Waves, electric, 690, 694

length of, 696, 702

velocity of propagation, 693
Wave length, standard, 706
Wave meter, 706
Wave winding, 575
Weber, 153

Weber's electro-dynamometer, 382
Weights, lifting by electro-magnets,

409

Welding, electric, 484
Weston A. C. ammeter, 467

D. C. voltmeter, 468

D. C. A. C. voltmeter, 470

standard cell, 213

Wheatstone bridge, arrangement of
resistances, 315

evolution in form, 316

measurement of resistances by, 317,
318, 319, 320, 321

principle of, 313, 314
Whirl, electric, 44
Wind, electric, 42, 44, 48, 49, 50
Wire carrying a current not a magnet,

349

Wire, circular measure of, 296
Wires, electric heating of, 480, 481
Wire gauges, 295
Wire tables, 295
Wireless telegraphy, 698

condition affecting, 707

distance attained by, 707
Work done by electric current, 47
Work in moving coil across field, 358

in moving conductor across field, 357
Work, unit of, 11

electric, commercial unit of, 496
X rays, 678, 679, 680, 684
Y connection, 647
Yoke, 561
Zincite as detector, 705



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Online LibraryWirt RobinsonThe elements of electricity → online text (page 46 of 46)