scholarly journals The polarization of a calomel electrode

1938 ◽  
Vol 125 (839) ◽  
pp. 283-290 ◽  
Keyword(s):  
Electric Current ◽  
Half Cell ◽  
Current Passing ◽  
Electric Current Passing ◽  
Current Flows ◽  
Definition Of

The object of this paper is to define, for electro-physiological purposes, the limits within which a calomel electrode is unaffected by electric current passing through it. The calomel half-cell, though always known as a non-polarizable electrode, is in fact polarizable in the same way as all other electrodes. The only difference between it and a notoriously polarizable electrode such as Pt is in degree. Since it is incorrect to talk of a calomel half-cell as a non-polarizable electrode, a definition of polarization is necessary: when a metal dips into a solution, there is a p. d. between it and the solution. Provided that (1) the composition of the electrode does not alter, (2) the activities of the components of the solution do not alter, and (3) no current flows through the system, the p. d. between the metal and the solution remains constant. If equilibrium does not exist between the metal and the solution, the p. d. does not remain constant and the metal becomes polarized. Thus polarization may be defined as the production of a thermodynamically irreversible potential at the surface of an electrode.

Magnetic polarity and neutrality

1883 ◽  
Vol 36 (228-231) ◽  
pp. 404-417
Keyword(s):  
Electric Current ◽  
Magnetic Polarity ◽  
Closed Circuit ◽  
Silk Fibre ◽  
Iron And Steel ◽  
Current Passing ◽  
Electric Current Passing ◽  
Electromagnetic Effects ◽  
Magnetic Needle

In recent papers upon the Theory of Magnetism, I gave the opinion drawn from a long series of personal researches, that magnetism in iron and steel is entirely due to the inherent polarity of its molecules, the force of which could neither be destroyed nor augmented; that, when we have evident magnetism, the molecules rotate so as to have all their similar polarities in one direction; and that neutrality is a symmetrical arrangement or a balancing of polar forces, as in a closed circuit of mutual attractions. The series of researches which I now present bear unmistakable testimony to the truth of these views, showing the opposite polarities which exist in an apparently neutral bar of iron; and that it is by this means alone that external neutrality occurs in the iron cores of an electro-magnet upon the cessation of the inducing current. The instrument used for measurements consists of a delicate silk fibre-suspended magnetic needle, always brought to its zero-mark by the influence of a large magnet at a distance, the angle of which gives the degree of force required to balance any magnetised body placed on the opposite side of the needle. It can also employ electromagnetic effects by the use of two opposing coils on each side of the needle, balanced so that an electric current passing through the coils has no influence on the needle, except when a piece of iron or steel is placed inside one of the coils; this again being balanced and measured by the large revolving magnet.

Enhancing CO2 methanation over a metal foam structured catalyst by electric internal heating

2020 ◽  
Vol 56 (2) ◽  
pp. 205-208 ◽  
Author(s):  
Liguang Dou ◽  
Cunji Yan ◽  
Liangshu Zhong ◽  
Dong Zhang ◽  
Jingye Zhang ◽  
...  
Keyword(s):  
Electric Current ◽  
Metal Foam ◽  
Joule Heat ◽  
Internal Heating ◽  
Ni Foam ◽  
Co2 Methanation ◽  
Heating Method ◽  
Current Passing ◽  
Structured Catalyst ◽  
Electric Current Passing

We develop an electric internal heating method based on a Ni-foam structured catalyst for CO2 methanation, in which the Joule heat generated by electric current passing through the catalyst drives the reaction.

scholarly journals The measurement of “accommodation” in nerve

1936 ◽  
Vol 119 (814) ◽  
pp. 355-379 ◽  
Keyword(s):  
Electric Current ◽  
Time Constant ◽  
Previous History ◽  
Low Frequency ◽  
Critical Value ◽  
Local Potential ◽  
Current Passing ◽  
Electric Current Passing ◽  
History Of ◽  
Short Time

When an electric current, insufficiently strong to excite, is removed from a nerve the “excitatory disturbance” (Lucas, 1910) or “local potential” (Hill, 1936) reverts to its resting value. The time-constant of this decay, assumed exponential, is the time- constant of excitation, k . If this assumption is correct, the chronaxie is 0·693 k . When an electric current passing through a nerve lasts for a very short time the critical value of the “local potential” required for excitation, that is the threshold, is constant. The previous history of the nerve is not involved and the only time-constant is k . If the current lasts for a longer time, as with constant currents near the rheobase, with linearly or exponentially increasing currents, or with low frequency alternating currents, the threshold rises: the threshold for a slowly increasing current is well-known to be higher than for a rapidly increasing one. This change in threshold is called “accommodation” (Nernst, 1908). If the rise in threshold occurs because of the rise in “local potential,” the threshold will revert to its resting value when the “local potential” reverts to its resting value. The time-constant of the return, assumed exponential, of the threshold to its resting level is λ, the time-constant of “accommodation.” If this assumption is correct, the time to half return is 0·693 λ.

scholarly journals Efficient Use of Carbon Fibers as Heating Elements for Curing of Epoxy Matrix Composites

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 5095
Author(s):  
Lykourgos C. Kontaxis ◽  
Ioannis E. Chontzoglou ◽  
George C. Papanicolaou
Keyword(s):  
Electric Current ◽  
Carbon Fibers ◽  
Epoxy Resins ◽  
Matrix Composites ◽  
Financial Benefit ◽  
Direct Electric Current ◽  
Current Passing ◽  
Three Point Bending ◽  
Electric Current Passing ◽  
Bending Mode

The aim of this study is to achieve a fully cured thermoset matrix that is heated by a direct electric current passing through the reinforcement fibers i.e., the Joule heating effect. Two types of fibers were used as heating elements for curing the epoxy resins. Kanthal resistance fibers were used as reference heating elements and subsequently, they were replaced by a Torayca Carbon Tow of the same radius. The specimens were cured by the heat produced by a direct electric current passing through the fibers and achieving temperatures of 50 °C and 70 °C. Specimens cured in a conventional oven were also manufactured, to compare the resistance heating method to the conventional one. Next, all specimens were mechanically characterized in a quasi-static three-point bending mode of loading and experimental results were compared to derive useful conclusions concerning the applicability of the technique to polymer/composite materials mass production. Finally, a preliminary economical study concerning power consumption needed for the application of both the traditional oven curing and the carbon fibers heating elements use for the manufacturing of the same amounts of materials is presented, showing a maximum financial benefit that can be achieved, on the order of 68%.

scholarly journals On a method of finding the conductivity for heat

1912 ◽  
Vol 87 (598) ◽  
pp. 535-539 ◽  
Keyword(s):  
Electric Current ◽  
The Body ◽  
Metallic Layer ◽  
Current Passing ◽  
Electric Current Passing ◽  
Small Grains

1. The method to be described for finding the conductivity for heat of a class of bad conductors may be considered to be an extension of a method given by one of us for finding the conductivity of substances mostly in the form of powder or small grains. In that paper the conductivity is inferred from the fall of temperature at different points from the axis of the mass, and the heat supplied to it by an electric current passing through a wire. In the present paper the body was in the form of flat layers, and the heat was supplied by passing an electric current through a thin metallic layer—in our case a piece of Dutch leaf. The leaf in the form of a rectangle was gummed to a piece of thin paper, and the current passed into it by two sheets of tinfoil also gummed to the paper and to the Dutch leaf along its opposite sides, the foil overlapping the leaf by spaces of about 1-2 mm., the two pieces of foil and the Dutch leaf forming a rectangle about 18 cm. long and 8 cm. wide, of which the Dutch leaf occupied the length of about 8 cm.

Sign in / Sign up

Export Citation Format

Share Document