Sources of Electricity

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.

How are Photoelectric devices classed?

According to the kind of cell they use: PHOTOVOLTAIC, PHOTOCONDUCTIVE & PHOTOEMISSION.

Electrons do not move to produce a current unless a _____ is applied to move them.

FORCE: Force is always necessary to produce action.

When a cell is not used constantly, it gradually deteriorates because of slow internal chemical action, called _____ _____, and its moisture content changes.

LOCAL ACTION

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).

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.

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.

What type of cell is a cadmium sulfide (CdS) cell?

PHOTOCONDUCTIVE

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.

Light-sensitive devices that convert light to electricity energy are called _____ devices.

PHOTOELECTRIC DEVICES

Producing voltage by exerting a pressure on a crystalline substance is called _____.

PIEZOELECTRIC EFFECT.

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.

As the light shines on a photovoltaic cell, the selenium loses electrons and becomes _____ charged.

POSITIVELY CHARGED

In which type of cell does the chemical action dissolve the negative plate, which cannot be recharged?

PRIMARY CELL.

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.

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.

The voltage or current capacity of a battery can be increased if _____.

two or more cells are connected together.

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.

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.

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.

What are the six primary methods of producing a voltage (EMF)?

Chemical action, Magnetism, Friction, Heat, Light and Pressure.

What is the purpose of a microphone?

Converts sound waves into electrical signals.

What type of primary cell is most frequently used?

DRY CELL

What are Photoelectric devices?

Devices that are sensitive to light and convert the light to electrical energy.

What are transducers?

Devices that change energy, such as mechanical energy, into EMF (electromotive force) or voltage.

Electricity in motion is called _____.

ELECTRICAL CURRENT: It is the flow of electrons in a conductor.

Photoelectric devices convert light energy into _____.

ELECTRICAL ENERGY.

Energy can be transferred from one placed to another through _____ in motion.

ELECTRICITY: Long transmission lines are examples of energy being transported long distances.

A source of electricity produced by chemical action is the ______.

ELECTROCHEMICAL CELL

The basic source of electricity produced by chemical action is the _____.

ELECTROCHEMICAL CELL

Electricity is produced by chemical action in a/an _____.

ELECTROCHEMICAL CELL.

Through which of the following do electrons move in an electrochemical cell?

ELECTROLYTE

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.

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.

The force that moves electricity originates when some form of energy, such as mechanical motion, is changed into an _____.

ELECTROMOTIVE FORCE OR VOLTAGE

The six primary methods of producing a voltage are chemical action, magnetism, friction, ____, _____ & _____.

HEAT, LIGHT & PRESSURE.

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.

The most common method of producing electricity is through _____.

MAGNETISM: Without magnetism, electricity could not be generated in the amount used today.

A device that converts sound waves into electrical signals through the piezoelectric effect is the crystal _____.

MICROPHONE

A natural crystalline material that has a piezoelectric effect is _____.

QUARTZ: Quartz crystals can be ground to vibrate at exact frequencies.

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.

Because a storage battery can be recharged, it is classified as a _____ cell.

SECONDARY CELL: Storage batteries can be recharged many times.

To INCREASE VOLTAGE, the positive electrode of one cell is connected to the negative electrode of the next. The cells are _____ _____.

SERIES CONNECTED

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.

SERIES-PARALLEL

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.

Rubbing a glass or rubber rod with a cloth produces a _____ charge on the rods.

STATIC CHARGE: Static charges are commonly produced by friction.

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.

What is a copper and iron wire junction called when heated to produce a voltage?

THERMOCOUPLE

Heat can be converted into electricity by heating a junction of two dissimilar metals called a _____.

THERMOCOUPLE: A thermocouple is a temperature-sensitive device.

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.