Voltage requirements

Sharpness. This describes the steepness of the electro-optical switching as a function of voltage. This is defined in tenns of the ratio of voltages required to achieve 90% compared to 10% transmission of light. This ratio should be as close to unity as possible. 

Cell Volta.ge a.ndIts Components. The minimum voltage required for electrolysis to begin for a given set of cell conditions, such as an operational temperature of 95°C, is the sum of the cathodic and anodic reversible potentials and is known as the thermodynamic decomposition voltage, is related to the standard free energy change, AG°C, for the overall chemical reaction,... 

The number of output voltages required and their partieular eharaeteris-ties. 

Electrical stability The test measures the voltage required to cause current flow between two electrodes immersed in an oil-base mud. The higher the voltage, the greater the stability and, consequently, the greater the drillpipe protection (see API RP 13B for more details [206]). 

The measurement of impedance voltage is defined as the voltage required circulating full-load current in one winding with the other windings short-circuited. It is common practice to express the leakage impedance, Z, of a transformer as a percentage (or per unit) value. The per unit value is ... 

Where a.c. supplies exist, transformer-rectifiers are the most economical source of d.c. for cathodic protection systems. In the case of pipelines, standard transformer-rectifiers, either oil or air cooled, can be employed. They range in size from 5A, 5V for small systems to 100 A, 48 V for major pipeline schemes. A typical output for a well-coated cross-country pipeline in the UK would be 5 A, 48 V. In the case of sea-water jetties where the voltage required is usually low because of the lower sea-water resistivity, a typical rectifier size for a major installation would be 500 A, 18 V. For offshore pipelines and loading platforms where a fire hazard exists, it is usual to employ certified flameproof or intrinsically safe rectifiers to overcome any possibility of fire hazard should faults develop in the unit. 

Groundbeds remote from the structure can be considered but usually with this type of installation problems arise due to damage to the connecting cable by ships anchors, etc. The calculation of rectifier voltage/anode resistance is exactly as described for impressed current pipeline installations except that the voltage required is very small because of the low resistance of the electrolyte—normally 20-3612 cm for typical sea-water. 

Consider the electrolysis of CuCl2 to form Cu(s) and Cl2(g). Calculate the minimum voltage required to carry out this reaction at standard conditions. If a voltage of 1.50 V is actually used, how many kilojoules of electrical energy are consumed in producing 2.00 g of Cu ... 

From Appendix 3, estimate the minimum voltage required to cause electrolysis of I M HC1, forming H2(g) and 0 (g), each at 1 atmosphere pressure. Show that at this voltage electrolysis to produce H2(g) and Cl (g) will not occur. 

Since the oxygen overvoltage on a platinum electrode is equal to 0.45 V, the minimum potential required for oxygen evolution is (+ 0.813 + 0.45) V or 1.263 V. Since the voltage required to implement this reaction is lower than that for a normal chlorine electrode, it follows that oxygen will be evolved at the anode in preference to chlorine. In contrast to the two possible reactions at the anode, there are five reactions that are possible at the cathode as shown below ... 

In the DC SQUID, two Josephson junctions are made in the loop, and a dc current is passed through the parallel circuit so formed. The voltage required to produce the current is then a function of the magnetic field trapped inside the loop. 

Fry John McCarron was saying that the voltage required for activation of STOCs was a bit more negative than this. 

Organic light-emitting display technology (see Table 8.2) overcomes these inherent weaknesses with its low operating voltage requirements (2 to 10 V), inexpensive DC driver... 

The Metal Partition Type.—In the preliminary escription of the filter press type of cell it was stated hat a conducting partition between the anode and athode itself became on one face an anode and on the ither face a cathode this, however, requires modifica-ion, as it is only true when the voltage drop between he original anode or cathode and the metal partition is ess than the minimum voltage required for continuous lectrolysis. 

Calculate the external voltage required to carry out the electrolysis. Why was the external voltage used in the investigation significantly higher than the calculated value ... 

Explain why you cannot use the table of standard reduction potentials in Appendix E to calculate the external voltage required to electrolyze molten sodium chloride. 

Fig. 10-27. Energy diagram for a cell of photoelectrolytic decomposition of water consisting of a platinum cathode and an n-type anode of titanium oxide (rutile) of which the Fermi level at the flat band potential is lower than the Fermi level of hydrogen redox reaction (ensc>< = external voltage required for cell reaction to occur S = aqueous solution.

---