Sources of Electricity

Energy can be transferred from one placed to another through _____ in motion.
ELECTRICITY: Long transmission lines are examples of energy being transported long distances.
Electrons do not move to produce a current unless a _____ is applied to move them.
FORCE: Force is always necessary to produce action.
A source of electricity produced by chemical action is the ______.
The solution through which electrons move from one battery plate to the other battery plate is called the ______.
ELECTROLYTE: It is a conducting solution that allows electrons to move easily between plates.
Because a dry cell cannot be recharged once it has completely discharged, it is called a _____ cell.
PRIMARY CELL: Once a primary cell is discharged it must be replaced.
All single dry cells when new have about _____ volts.
1.5 VOLTS: This is the maximum voltage that can be produced by a single dry cell.
Higher battery voltages can be obtained by connecting the cells in _____.
SERIES: The total voltage is the sum of the voltages of the individual cells.
Higher battery current output is obtained when cells are connected in _____.
PARALLEL: The voltage is the same as that of one cell, but each cell adds to the total amount of current.
Because a storage battery can be recharged, it is classified as a _____ cell.
SECONDARY CELL: Storage batteries can be recharged many times.
To restore a storage battery to a fully charged condition, electricity current is forced through the battery in the reverse direction by a _____.
CHARGER: A charger can be an alternator in a car, a generator, or an electrical rectifier.
The most common method of producing electricity is through _____.
MAGNETISM: Without magnetism, electricity could not be generated in the amount used today.
Rubbing a glass or rubber rod with a cloth produces a _____ charge on the rods.
STATIC CHARGE: Static charges are commonly produced by friction.
Heat can be converted into electricity by heating a junction of two dissimilar metals called a _____.
THERMOCOUPLE: A thermocouple is a temperature-sensitive device.
As the junction of a copper and iron thermocouple is heated, the electrons in the copper move from the _____ end to the _____ end.
HOT;COLD: Because the electrons in the iron strip move from the cold end to the hot end.
In actual practice, a voltmeter is connected to the free ends of a thermocouple and is calibrated in _____ _____.
TEMPERATURE DEGREES: A voltmeter is calibrated for temperature in degrees and it gives a direct temperature reading.
When several thermocouples are connected together, they form a _____.
THERMOPILE: Because of the low voltage generated by one thermocouple, several are connected to increase the voltage output.
Light-sensitive devices that convert light to electricity energy are called _____ devices.
As the light shines on a photovoltaic cell, the selenium loses electrons and becomes _____ charged.
Depending on the amount of light that strikes a cell, the resistance of a _____ cell varies.
PHOTOCONDUCTIVE CELL: The varying resistance controls the amount of current in the circuit.
One type of photoconductive cell is the _____ or CdS cell.
CADMIUM SULFIDE OR CdS CELL: The cell's sensitivity to light variations provides measurement of low light levels.
In a photoemission cell, electrons are emitted directly from teh surface of the _____.
CATHODE: Other photoelectric devices change internally to allow current flow.
A crystalline material produces a voltage under pressure, which is called the _____ effect.
PIEZOELECTRIC EFFECT: The amount of voltage produced varies with the amount of pressure.
A natural crystalline material that has a piezoelectric effect is _____.
QUARTZ: Quartz crystals can be ground to vibrate at exact frequencies.
A device that converts sound waves into electrical signals through the piezoelectric effect is the crystal _____.
Electricity in motion is called _____.
ELECTRICAL CURRENT: It is the flow of electrons in a conductor.
The force that moves electricity originates when some form of energy, such as mechanical motion, is changed into an _____.
What are transducers?
Devices that change energy, such as mechanical energy, into EMF (electromotive force) or voltage.
What are the six primary methods of producing a voltage (EMF)?
Chemical action, Magnetism, Friction, Heat, Light and Pressure.
The basic source of electricity produced by chemical action is the _____.
Electrons move from one plate of the battery to the other plate through a solution called the _____.
ELECTROLYTE: The electrons are conducted from one plate to the other by a chemical reaction between electrolyte and the two plates.
What is a primary cell?
A type of cell that once it has been completely discharged, it cannot be charged again unless new materials are used.
What type of primary cell is most frequently used?
The voltage or current capacity of a battery can be increased if _____.
two or more cells are connected together.
To INCREASE VOLTAGE, the positive electrode of one cell is connected to the negative electrode of the next. The cells are _____ _____.
To INCREASE CAPACITY, a _____ connection is used so the current capacity of all the cells is the sum of the capacities of the individual cells
PARALLEL: All the cells act together as a single cell, and the voltage is the same as that of an individual cell.
To provide adequate power when both VOLTAGE and CURRENT requirements are greater than the capacity of one cell, a combination _____ network of cells is used.
When a cell is not used constantly, it gradually deteriorates because of slow internal chemical action, called _____ _____, and its moisture content changes.
What type of cells can be restored to their original condition by forcing an electric current to flow through them in the opposite direction of discharge.
SECONDARY CELL: A storage battery is a common example of a secondary cell.
What are the three kinds of secondary cells?
Lead-acid, nickel-alkali and nickel-cadmium-alkali. (Acid and Alkali are the electrolytes used in the batteries).
What is a thermopile?
A combination of several thermocouples. It can increases voltage output and measures the heat intensity for a given operation. By connecting the thermopile to a control, the heat can be kept at a set temperature.
What are Photoelectric devices?
Devices that are sensitive to light and convert the light to electrical energy.
How are Photoelectric devices classed?
According to the kind of cell they use: PHOTOVOLTAIC, PHOTOCONDUCTIVE & PHOTOEMISSION.
The six primary methods of producing a voltage are chemical action, magnetism, friction, ____, _____ & _____.
Electricity is produced by chemical action in a/an _____.
Through which of the following do electrons move in an electrochemical cell?
In which type of cell does the chemical action dissolve the negative plate, which cannot be recharged?
Which symbol below represents a battery cell?
What is a copper and iron wire junction called when heated to produce a voltage?
Photoelectric devices convert light energy into _____.
What type of cell is a cadmium sulfide (CdS) cell?
Producing voltage by exerting a pressure on a crystalline substance is called _____.
What is the purpose of a microphone?
Converts sound waves into electrical signals.