Practical Electricity: A Laboratory and Lecture Course for First Year Students of Electrical Engineering, Based on the International Definitions of the Electrical Units, Volume 1

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Cassell, limited, 1897 - Electricity - 643 pages
 

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Contents

Experiinent for Calibrating à Galvanometer Relatively or Absolutely
12
Graphically Recording the Results of an Experiment
13
Practical Value of Drawing Curves to Graphically Record the Results of Experiments
14
To Construct a Galvanometer Scale from which the Relative
15
Strengths of Currents can be at once Ascertained 39
24
SECTION PAGE
53
The Potential of a Body Depends Partly on its Position
60
GALVANOMETERS AND AMMETERS
63
Distribution of Magnetism in a Permanent Magnet 17 Magnetic Poles 18 Why Magnetic Needles tend to Point North and South
67
Why a Galvanometer Needle has a Given Deflection for a Given Current
69
Mapping out Lines of Force
71
Comparing the Relative Strength of the Different Parts of a Magnetic Field
79
Tangent Galvanometer
83
SECTION PAGE 24 Scale for a Tangent Galvanometer
87
Tangent Law 26 Variation of the Sensibility of a Tangent Galvanometer with
91
the Number of Windings and with the Diameter of the Bobbin
95
Values in Amperes of the Deflections of a Tangent Galvano meter controlled only by the Earths Magnetism
102
Magnetometer 29 Calibrating any Galvanometer by Direct Comparison with
107
a Tangent Galvanometer
108
Pivot and Fibre Suspensions
110
Sine Law
111
Employment of the Sine Principle in Galvanometers
118
Construction of Galvanometers in which the Angular Deflec tion is directly Proportional to the Current
124
Galvanometers of Invariable Sensibility
127
Permanent Magnet Ammeter
130
Adjusting the Coil of a Tangent Galvanometer 69
132
71
135
Gravity Control Ammeters
138
Moving Coil Ammeters
144
Moving Coil Ammeter with Magnetic Control
150
CHAPTER III
152
and Negative Potentials
160
Electrometer
162
Ohms Law
167
Resistance
172
Ohm
173
Volt
174
Current Method of Comparing P Ds
176
all Points Inside a Closed Conductor
197
Voltmeters must be Enclosed in a Conducting Case
198
The Potential of a Conductor
200
CHAPTER IV
232
Increase of the Main Current Produced by Applying a Shunt
298
Method of Constructing a Universal Shunt Box and
304
Heat Produced by a Current
318
Power
325
Commercial Forms of Wattmeters
331
Motor Form
341
Board of Trade Unit of Energy
349
Power Developed by a Current Generator
358
GALVANIC CELLS
360
Connection between the E M F of a Battery the P D
364
Power Absorbed in the Circuit Exterior to the Generator
370
A Current Generator may Abstract Energy from a Circuit
381
Arrangement of Part of the External Circuit to Receive
393
Efficiency
404
Connection between Electrical Efficiency of Transmission
412
TYPES CONSTRUCTION CHEMICAL ACTION RELATIVE ADVANTAGES
418
Local or Prejudicial Action
428
Bunsens Cell
443
Leclanché Cell
449
Dry Cells
457
Clarks Cell
466
Temperature Variation of the E M F of the Clarks Cell
475
Cost of Producing
482
Measuring a Cells Resistance when Very Small
492
Remarks on the Preceding Methods of Measuring
498
Poggendorffs Method of Comparing Electromotive Forces
507
Fosters Method of Subdividing a Wire into Lengths having
513
Use of a Clarks Cell and a Known Resistance as a Standard
519
Independence of Currents in Parallel Circuits
525
Arrangements of Cells
536
Arrangement of a Given Number of Cells to produce
545
Arrangement of Circuit requiring the Minimum Number
555
Minimum Number of Cells Required to Produce a Given
560
Magnetic Lines of Force Diagrams II The Preparation and Use of Silk for Galvanometer
565

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Page 591 - Ampere, which is one-tenth of the unit of current of the CGS system of electromagnetic units and which is represented sufficiently well for practical use by the unvarying current which, when passed through a solution of nitrate of silver in water, in accordance with a certain specification, deposits silver at the rate of 0.001118 of a gramme per second.
Page 585 - As a unit of resistance, the international ohm, which is based upon the ohm equal to 10" units of resistance of the CGS system of electromagnetic units, and is represented by the resistance offered to an unvarying electric current by a column of mercury at the temperature of melting ice, 14.4521 grams in mass, of a constant cross-sectional area and of the length of 106.3 centimetres.
Page 587 - ... the electromotive force that, steadily applied to a conductor whose resistance is one international ohm, will produce a current of...
Page 586 - The unit of current shall be what is known as the international ampere, which is one-tenth of the unit of current of the centimeter-gramsecond system of electro-magnetic units, and is the practical equivalent of the unvarying current, which, when passed through a solution of nitrate of silver in water in accordance with standard specifications, deposits silver at the rate of one thousand one hundred and eighteen millionths of a gram per second.
Page 466 - ... carefully removing any loose pieces of the zinc. Just before making up the cell dip the zinc into dilute sulphuric acid, wash with distilled water, and dry with a clean cloth or filter paper.
Page 466 - Mix the washed mercurous sulphate with the zinc sulphate solution, adding sufficient crystals of zinc sulphate from the stock bottle to ensure saturation, and a small quantity of pure mercury. Shake these up well together to form a paste of the consistence of cream. Heat the paste, but not above a temperature of 30° C.

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