Guide to the Practical Elements of Electrical Testing |
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Page 38
... standard employed in this connection is therefore Clark's Standard Cell , the E.M.F. of which is approximately 1.454 B.A. volts at 15 degs . C. The Clark's cell possesses electrodes of pure zinc , and similarly pure mercury , exposed to ...
... standard employed in this connection is therefore Clark's Standard Cell , the E.M.F. of which is approximately 1.454 B.A. volts at 15 degs . C. The Clark's cell possesses electrodes of pure zinc , and similarly pure mercury , exposed to ...
Page 41
... cell , and with the mercury in the other , by means of platinum wires sealed through the glass . " Marine Clue Cork ... Standard Cell . - Clark's standard cell , as specified by the Board of Trade , is almost universally adopted as a ...
... cell , and with the mercury in the other , by means of platinum wires sealed through the glass . " Marine Clue Cork ... Standard Cell . - Clark's standard cell , as specified by the Board of Trade , is almost universally adopted as a ...
Page 42
... standards is required . It is of these modifications , and their several merits and demerits , that I pro- pose ... Standard Cell . Zinc Sulph . Crys . Zinc Amalgam Manne Glue Cork Zine Sulphate Mercurous Sulph . Paste Mercury FIG ...
... standards is required . It is of these modifications , and their several merits and demerits , that I pro- pose ... Standard Cell . Zinc Sulph . Crys . Zinc Amalgam Manne Glue Cork Zine Sulphate Mercurous Sulph . Paste Mercury FIG ...
Page 43
... standard cell , as enunciated by Mr. John Hender- son , D.Sc. , F.R.S.E. , in a recent article on the subject , which appeared in the Electrical Engineer . They are as follows : 66 - ( 1 ) The standard cell must be easily made and repro ...
... standard cell , as enunciated by Mr. John Hender- son , D.Sc. , F.R.S.E. , in a recent article on the subject , which appeared in the Electrical Engineer . They are as follows : 66 - ( 1 ) The standard cell must be easily made and repro ...
Page 44
... standard , it will be seen that , should the cell be at any time inadvertently upset or otherwise inverted , as in transit , for instance , the mercury which forms the lower electrode would tend to displace the other elements of the cell ...
... standard , it will be seen that , should the cell be at any time inadvertently upset or otherwise inverted , as in transit , for instance , the mercury which forms the lower electrode would tend to displace the other elements of the cell ...
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Common terms and phrases
adjustable arm alternating current ammeter ampère apparatus cable under test calibration capacity charging circuit key Clark Cell Co-eff coil conductor connected consists constant constructed copper D'Arsonval D'Arsonval Galvanometer Daniell cell deflection method deflection results depressed described discharge disconnected drum earth ebonite electrode electromotive force Elliott Bros extremity fault galvano glass high resistance immersed indicated in Fig instrument insulation resistance known latter leakage length lever localisation loop low resistance magnetic megohms mercurous sulphate mercury meter metre bridge millimetre mounted Nalder Bros nected needle noted Ohm's law ohms ordinary platinum plugs pole practical reading reflecting galvanometer represented in Fig resistance measurement respectively scale short circuit shown shunt sistance slide wire slider standard cell standard resistance suitable surface suspended switch temperature terminals testing battery tion total resistance tube usually vanometer voltage voltmeter volts Wheatstone bridge whilst zero zinc sulphate
Popular passages
Page 40 - ... above the cork, using sufficient to cover completely the zinc and soldering. The glass tube containing the platinum wire should project some way above the top of the marine glue. The cell may be sealed in a more permanent manner by coating the marine glue, when it is set, with a solution of sodium silicate, and leaving it to harden.
Page 50 - 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 39 - Sulphate. — Take mercurous sulphate, purchased as pure, mix with it a small quantity of pure mercury, and wash the whole thoroughly with cold distilled water by agitation in a bottle; drain off the water, and repeat the process at least twice. After the last washing, drain off as much of the water as possible.
Page 40 - Then insert the cork and zinc rod, passing the glass tube through the hole prepared for it. Push the cork gently down until its lower surface is nearly in contact with the liquid. The air will thus be nearly all expelled, and the cell should be left in this condition for at least...
Page 39 - ... any free acid. The crystals should be dissolved with the aid of gentle heat, but the temperature to which the solution is raised should not exceed 30
Page 40 - ... which the zinc rod can pass tightly ; at the other side bore another hole for the glass tube which covers the platinum wire; at the edge of the cork cut a nick through' which the air can pass when the cork is pushed into the tube.
Page 39 - C. Keep the paste for an hour at this temperature, agitating it from time to time, then allow it to cool ; continue to shake it occasionally while it is cooling. Crystals of zinc sulphate should then be distinctly visible, and should be distributed throughout the mass ; if this is not the case, add more crystals from the stock bottle, and repeat the whole process. This method ensures the formation of a saturated solution of zinc and mercurous sulphates in water. To set up the Cell. The cell may conveniently...
Page 38 - ... 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 40 - ... the glass tube which covers the platinum wire ; at the edge of the cork cut a nick through which the air can pass when the cork is pushed into the tube. Wash the cork thoroughly with warm water, and leave it to soak in water for some hours before use.