Current, Continuous.
A current of one direction only; the reverse of an alternating current.
(See Current, Alternating.)
Current, Critical.
The current produced by a dynamo at its critical speed; at that speed
when a slight difference in speed produces a great difference in
electro-motive force. On the characteristic curve it corresponds to the
point where the curve bends sharply, and where the electro-motive force
is about two-thirds its maximum.
Current, Daniell/U.S. , Daniell/Siemens' Unit.
A unit of current strength used in Germany. It is the strength of a
current produced by one Daniell cell in a circuit of the resistance of
one Siemens' unit. The current deposits 1.38 grams of copper per hour.
It is equal to 1.16 amperes.
Current, Demarcation.
In electro-therapeutics, a current which can be taken from an injured
muscle, the injured portion acting electro-negatively toward the
uninjured portion.
Current Density.
The current intensity per unit of cross-sectional area of the conductor.
The expression is more generally used for electrolytic conduction, where
the current-density is referred to the mean facing areas of the
electrodes, or else to the facing area of the cathode only.
The quality of the deposited metal is intimately related to the current
density. (See Burning.)
Proper Current Density for Electroplating
Amperes Per Square Foot of Cathode.--(Urquhart.)
Copper, Acid Bath. 5.0 to 10.0
" Cyanide Bath, 3.0 " 5.0
Silver, Double Cyanide, 2.0 " 5.0
Gold, Chloride dissolved in Potassium Cyanide, 1.0 " 2.0
Nickel, Double Sulphate, 6.6 " 8.0
Brass, Cyanide, 2.0 " 3.0
Current, Diacritical.
A current, which, passing through a helix surrounding an iron core,
brings it to one-half its magnetic saturation, q. v.
Current, Diaphragm.
If a liquid is forced through a diaphragm, a potential difference
between the liquid on opposite sides of the diaphragm is maintained.
Electrodes or terminals of platinum may be immersed in the liquid, and a
continuous current, termed a diaphragm current, may be taken as long as
the liquid is forced through the diaphragm. The potential difference is
proportional to the pressure, and also depends on the nature of the
diaphragm and on the liquid.