18WuD2x

end point • energy-level diagram 259
Magnet
Magnet
Negative
electrode
Electron path
Electron path
Plate
end-plate magnetron
Plate
Magnet
Cathode
Positive
electrode
Cathode
Magnet
lead-acid storage cell, the specific-gravity value
of the electrolyte at which the cell is considered
in need of recharging (nominally 1.150 to
1.175).
end-point control A form of quality control in
which the end item is checked for defects.
end-point sensitivity A means of expressing the
sensitivity of a meter or other indicating device:
the ratio, in decibels, between the input signal
required to produce a full-scale or maximum
reading and the smallest detectable input signal.
end-point voltage The voltage of a battery or cell
terminal when the device is no longer useful.
end resistance In a rheostat or potentiometer, the
resistance between the wiper and the end terminal
when the wiper is set to the end point of the
device.
end-resistance offset In a potentiometer, the resistance
between the wiper and an end terminal
when they are in contact.
end-scale deflection See END-SCALE VALUE.
end-scale value For an indicating meter, the electrical
quantity indicated at the last graduation on
the scale.
end section Either the input or output section of a
multisection filter.
end setting 1. The fully clockwise or fully counterclockwise
setting of a rotatable control. 2. The
minimum or maximum setting of a control.
end shield In a magnetron, a shield that confines
the space charge to the interaction space.
end spaces The cavities at either end of the anode
block in a multicavity magnetron tube; they terminate
all the anode-block cavity resonators.
end use The intended application of a circuit or device.
energize To apply operating power and input signals
to a circuit or device.
energized The condition of a circuit or device that
is powered or excited.
energy Symbol, W. Common units: joule, watthour,
and kilowatt-hour. 1. The capacity for doing
work. Some common forms of energy are
electrical, mechanical, and chemical. Also see
CONSERVATION OF ENERGY, KINETIC EN-
ERGY, and POTENTIAL ENERGY. 2. The work
performed by electric power. The unit used by
utility companies is the kilowatt-hour (kWh),
equal to the product Pt, where P is power in kilowatts
and t is the period (hours) during which the
power is used.
energy-band diagram A diagram depicting the various
energy levels within the atom of a conductor,
semiconductor, or insulator.
energy barrier The natural potential gradient
across a semiconductor junction. In the absence
of an applied voltage, the gradient, not measurable
from the outside, prevents total interaction
between the n- and p-type materials.
energy cell 1. A usually small primary or secondary
cell—especially the kind used in hearing
aids and electronic watches. 2. A capacitivetype
direct-current (dc) source (see ENERGY-
STORAGE DEVICE, 2).
energy consumption 1. The conversion of energy
from one form to another by a component, circuit,
system, or machine, in the process of performing
some useful task. 2. The amount of energy involved
in the process defined in 1.
energy conversion The transformation of energy
from one form to another. See also CONSERVA-
TION OF ENERGY and ENERGY TRANSFORMA-
TION.
energy-conversion device A component, circuit,
system, or machine that changes energy from one
form to another. See also CONSERVATION OF
ENERGY.
energy density 1. For an energy-producing cell,
such as an electrochemical cell, the ratio of available
energy to cell mass. It is expressed in joules
per gram or in watt-hours per kilogram. 2. For
an energy-producing cell, the ratio of available
energy to cell volume. Expressed in joules per cubic
centimeter or in watt-hours per cubic centimeter.
energy gap In the energy-level diagram for a semiconductor
or insulator, the region between valence
and conduction bands representing the
minimum energy required to make the electron
pass from the valence to the conduction band
(i.e., to become a current carrier). Also called forbidden
energy band.
energy level A constant-energy state, such as one
of the energy levels of an electron in an atom.
energy-level diagram 1. A diagram showing the
energy levels (in electronvolts) of electrons in the
various shells of an atom. 2. A diagram showing
variations in power that correspond to variations
in current in a channel.