homestudy 2 Flashcards

Terms Definitions
Selenium is a...
Semiconductor
Resistance is measured with a(n)
ohmmeter
Piezoelectricity refers to electricity produced by some materials when they are subjected to
pressure
When resistors are manufactured, the processes are not perfectly exact. Each resistor may be slightly different from the next one. The plus and minus limits of a resistor's ohmic value is called
Tolerance
Finding the values of voltage, current, resistance, and power in a series circuit can be found by using ___ law
Ohm's
Reading current without being required to connect the meter in series in the circuit is often desirable. This can be done using a ___ ammeter
clamp-on
A voltmeter has a ___internal resistance
high
The nonconductive covering around a wire is the
insulation
The measurement of the specific gravity of an electrolyte in a secondary cell is done with a device called a(n)
hydrometer
The most common method of producing electricity is through the use of
Magnetism
Valence electrons are contained in the ____ shell
Outermost
In a parallel circuit, the voltage drop across any branch is the same as the ____ voltage
applied
In a parallel circuit, the total current flow is equal to the ____ of the currents through all the branches
Sum
The meter that measures power is the
wattmeter
In the National Electrical Code, the current carrying abilities of conductors are called
ampacities
An ammeter has a ___ internal resistance
low
The ampacities listed in the tables are based on a specified ambient temperature. If conductors are to be operated in a different ambient temperature than the temperature specified, a ____ factor must be applied
correction
As a conductor diameter is changed, the circular mil area will change. If a conductor diameter is changed so that the circular mils double, the conductor resistance will
halve
The lead-acid batteries used in automobiles are made with an electrolyte containing
sulfuric acid
In 1800 Alessandro Volta was experimenting with producing electricity and created the first battery constructed of individual cells connected together, which he called a
voltaic pile
In an electrical circuit, the voltage is 50 volts and the resistance is 5 watts. What is the value of current?
10 A
Resistors which only have one ohmic value called
Fixed resistors
A three-resistor circuit has a total power of 25 W. Two of the resistors dissipate 10W and 5W respectively. How much power does the third resistor dissipate?
10 W
An increase in ____ results in an increase of load in a parallel circuit
Current
In a parallel circuit, the total resistance is always ___ resistance of the lowest value resistor
Less than
In a series circuit, all voltage drops across all the resistors are ____ to determine the voltage applied to the circuit
Added
A meter movement that uses the taut band suspension and operates on very tiny amounts of current is often called a
galvanometer
The "ambient air temperature" that is considered in relation to a conductor ampacity is the temperature of the
surrounding air
In order for ammeters to read currents higher than the meter movement maximum current, a ___ is connected in parallel with the meter movement
shunt
On a _____, it is necessary to readjust the meter to zero when the scale is changed
ohmmeter
In a secondary cell, an electrolyte can be checked to ensure that it has correct chemical composition by measuring its
specific gravity
When a one-loop generator's speed of rotation is increased, the conductor cuts more lines of flux per second, resulting in a higher
induced voltage
A battery can have two voltage ratings, one measured with no load and one measured at normal load. This is because the battery has
internal resistance
A thundercloud can obtain ____ and ____ charges
Positive and negative
Short circuits generally cause a ____ to blow, or a ____ to open
Fuse; circuit breaker
A resistor has color bands of brown, black, red, and silver. What is the resistance and tolerance of the resistor?
100W, 10%
Within a lightning bolt, current always flows
From negative to positive
The atomic number of an element is the number of ____ in the nucleus
Protons
A parallel circuit composed of a 10 ohm and a 22 ohm resistor. It has a supply voltage of 60 V. What is the current in the 10 ohm resistor?
6 A
In a series circuit the current is ____at any point in the circuit
The same
"The algebraic sum of the currents entering and leaving a point must equal zero" is which law?
Kirchhoff's current law
As lead-acid batteries age, they may lose some of their capacity. To load test a battery, a load of THREE TIMES the ampere-hour rating is connected to the battery. The voltage is monitored and after _____, the voltage should be above ___% of the terminal
3 minutes; 80%
If current is flowing in a circuit containing an inductor and the power switch is opened, it is possible that a ____ may be created
voltage spike
The plate metals used in a battery are chosen based on how easily one metal will give up electrons compared to the other metal. A list of metals showing their willingness to accept or receive electrons is called the _____ series of metals
electromotive
Each cell of a ni-cad battery creates ____ volts, resulting in a six cell battery having a terminal voltage of ___ volts
1.2V; 7.2V
The toner in a copy machine sticks to the drum in areas that...
Are charged
In a combination circuit, how should one identify the series and parallel elements?
Trace the current path
A piece of wire that is 0.001 inches in diameter and 12 inches long is
one mil-foot
If a magnesium atom combines with two chlorine atoms, the result is
a metallic salt
The most accepted theory as to why current flows is
The Electron Flow Theory
Wires of different sizes are labeled with respect to their diameter. The identifying scale that is used is the __ scale (formerly known as the Brown and Sharpe scale).
AWG scale (American Wire Gauge)
When DC is applied to a coil, the rate of current increase is described by a(n)
exponential curve
If a thundercloud has a positive charge, the current in the lightning bolt will in what direction?
From the earth to the cloud
A coil has an inductance of 3 H and a wire resistance of 15 W. How long will it take for the current to reach its full value?
1.0 seconds
The three formulas used to determine resistance in a parallel circuit are called
Resistors of Equal Value, Product Over Sum, Reciprocal Formula
When a cell cannot be recharged by design, it is due to
a chemical reaction which causes the electrodes to be eaten away
If a voltage is being induced into a conductor by electromagnetic induction, reversing the direction of motion of the conductor will
reverse the polarity of the induced voltage
In a circuit, three wires form a junction. the current in one of the wires is
the sum of the currents in the other two wires; and the difference between the currents of the other two wires
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