Mechanics of the Household: A Course of Study Devoted to Domestic Machinery and Household Mechanical AppliancesKeene, E. S. (Edward Spencer)
Science
Mechanics of the Household: A Course of Study Devoted to Domestic Machinery and Household Mechanical Appliances
Keene, E. S. (Edward Spencer)
Heating; Lighting; Plumbing
=The Electric Toaster.=--As shown in Fig. 229 the toaster is made of
a series of heating elements mounted on mica frames and supported on
a porcelain base. It is an example of heating by exposed wires and
direct radiation. The heaters _H_ are coils of flat resistance wire
that are wound on wedge-shaped pieces of mica. They are supported on a
wire frame that is formed to receive slices of bread on each side of
the heaters. The attachment piece _A_ and the material of the heater is
similar in construction to that of the flat-iron. The electric circuit
may be traced from the contacts at _A_ and _B_ in the attachment plug
by the dotted lines which indicate the wires in the porcelain base.
The current traverses each coil in turn and connects with the next,
alternately at the top and bottom. The resistance is such as will
permit the voltage of the circuit to send through the coils current
sufficient to raise the heaters to a red heat. The added resistance of
the hot wires decreases the flow of current to keep the temperature at
the desired degree.
[Illustration: FIG. 229.--The electric toaster.]
In a heater of this kind the resistance of the wire may increase with
age and the coils fail to glow with a sufficient brightness. The
reason for the lack of heat is that of decrease in current, due to the
increased resistance of the wires. This condition may be corrected by
the removal of a little of the heater coils. If a turn or two of the
heater wire is removed, the resistance of the circuit is reduced and
the effect of the increased current will produce a higher temperature
in the heater.
=Motors.=--As a means of developing mechanical power in small units,
the electric motor has made possible its application in many household
uses that were formerly performed entirely by manual labor. As a
domestic utility electrical power is generated at a cost that is the
least expensive of all its applications. As a means of lighting and
heating electricity has had to compete with established methods and has
won place because of the advantages it possesses over that of cost.
In the development of domestic power it has practically no opponent.
There is no other form of power that can be so successfully utilized
in delivering mechanical work for the purposes required. A kilowatt of
electric energy, for which 10 cents is a common price, will furnish a
surprising amount of manual labor. Theoretically, 746 watts is equal to
1 horsepower. The commercial kilowatt is rated at an hour of time, and
is, therefore, equal theoretically to 1-1/3 horsepower for one hour.
While motors cannot be expected to transform all of this energy into
actual work without loss, even at the low rate of efficiency attained
by the small electric motor, they furnish power at a relatively small
cost.
Public-domain text, read in full here on John Shaqi.
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