Basic Electricity Flashcards
What is the most important law applicable to the study of electricity?
Ohm’s Law E= I x R
What are the elements of ohms law?
Voltage, current, resistance
what are four sources of electrical energy?
Thermal, light, pressure and chemical
what does an electrical circuit consist of?
A source, resistance or load, and conductors
what represents capacitance in an AC circuit?
Capacitor
what is the function of a capacitor?
to store electricity
what is the unit of measure for capacitance?
Farad
what is the standard unit of measure for frequency?
Hertz
what is the basic component that only allows current to flow in one direction?
Diode (acts like a check valve)
What is inductance?
opposition to the flow of current in an AC circuit offered by a coil
What is an example of an inductor in a magneto?
the Coil
what is impedance?
The total resistance in a circuit
what causes opposition to the flow of current in an AC circuit?
Inductive, and capacitive reactance
What is the unit of measurement for impedance?
Ohms
what is a general purpose of a resistor?
to limit current
how may the value of a small, fixed resistor be determined?
By the color bands of the resistor
what are the two things that happen when current flows through a conductor?
Magnetic field is generated and the conductor heats up
what is the common name for the lines of force that make up a field surrounding a magnet?
Magnetic flux lines
what is the concept that describes the relationship between electricity and magnetism?
Electromagnetism
what are the four factors that affect the resistance of an electrical conductor?
Wire gauge, length, temperature, and material
What is the unit of measurement of power in a DC circuit?
the Watt. P = I x E
What is a kilowatt?
1,000 Watts Kilo means thousand
In a DC circuit, what occurs when voltage is increased while resistance remains constant?
There will be an increase in current.
What are the three types of DC electrical circuits?
Series, compound, parallel
A 24-Volt lead acid battery has how many cells ?
12 cells each is approx. 2 volts
what are the units that a battery capacity is measured in?
Ampere-hours
what should be the specific gravity of the electrolyte in a fully charge lead acid battery?
Should be between 1.275 and 1.300
what instrument is used to determine specific gravity of electrolyte in lead acid battery?
Hydrometer
why can a hydrometer not be used to determine the charge of NiCad battery?
The specific gravity of the electrolyte and NiCad battery does not change appreciatively during charge or discharge.
When using a hydrometer to check the charge of a lead acid battery, at what temperature must a correction factor be applied to the reading?
above 90°F and below 70°F adjustments must be made
what is electromagnetic induction?
The transfer of electrical energy by means of magnetic field. Transferring voltage from one conductor to another without physical touching.
How are battery compartments protected against corrosion?
They are coated with special corrosion resistant paint such as bituminous paint.
What should be the correct electrolyte level in a properly serviced battery?
It should be approximately 3/8 of an inch above the plates. If battery has baffle plates above cell plates, the electrolyte levels should be up to the hole in the baffle plate in each cell.
What are paralleling generators and how is the load distributed?
When two or more generators are operated at the same time to supply power for a load that must be shared equally.
Describe a trip free circuit breaker?
Is impossible to manually hold circa close when excessive current is flowing
can you store NiCad and lead acid batteries together?
no because cross contamination can occur
what is the result of an imbalance cell in a NiCad battery?
Current will increase across the cell causing it to heat up
what happens to the specific gravity of electrolyte and lead acid battery when the temperature changes?
it follows temperature
high temp = higher specific gravity reading
low temp = lower specific gravity reading
What is an LED?
Light Emitting Diode
What is an SLA battery?
Sealed Lead Acid Battery
What is the basic unit of measure for inductance?
Henry
What prevents reverse current flow in a DC alternator?
Reverse current cutout
How many wires may be installed in a single terminal lug?
4
how do you identify wire types?
Lettering on the insulation
what is the max number of terminals I can be attached to a terminal strip stud?
More than four terminal lugs or three terminal lugs and a bus bar
