Universal Battery System.
A term in telegraphy. If several equal and high resistance telegraphic
circuits are connected in parallel with each other from terminal to
terminal of a battery of comparatively low resistance each circuit will
receive the same current, and of practically the same strength as if
only one circuit was connected. This is termed the universal battery
system. It is a practical corollary of Ohm's law. The battery being of
very low resistance compared to the lines the joining of several lines
in parallel practically diminishes the total resistance of the circuit
in proportion to their own number. Thus suppose a battery of ten ohms
resistance and ten volts E. M. F. is working a single line of one
hundred ohms resistance. The total resistance of the circuit is then one
hundred and ten ohms. The total current of the circuit, all of which is
received by the one line is 10/110 = .09 ampere, or 90 milliamperes. Now
suppose that a second line of identical resistance is connected to the
battery in parallel with the first. This reduces the external resistance
to fifty ohms, giving a total resistance of the circuit of sixty ohms.
The total current of the circuit, all of which is received by the two
lines in equal parts, is 10/60 = .166 amperes. But this is equally
divided between two lines, so that each one receives .083 ampere or 83
milliamperes; practically the same current as that given by the same
battery to the single line. It will be seen that high line resistance
and low battery resistance, relatively speaking, are required for the
system. For this reason the storage battery is particularly available.
The rule is that the resistance of the battery shall be less than the
combined resistance of all the circuits worked by it.
Unmarked End.
The south-seeking pole of a magnet, so called because the other end,
called the marked end, is usually marked with a scratch or notch by the
maker, while the south pole is unmarked.
V.
(a) Symbol for velocity.
(b) Symbol or abbreviation for volume.
(c) Symbol or abbreviation for volt.