Basic Electricity Flashcards
(46 cards)
1
Q
- What is the most important law applicable to the study of electricity?
A
Ohm’s Law (E=I x R)
2
Q
- What are the elements of Ohm’s Law?
A
Voltage(E), Current(I), Resistance(R)
3
Q
- What are the four sources of electrical energy?
A
Thermal, light, pressure, and chemical
4
Q
- What does an electrical circuit consist of?
A
Source (battery)
Resistance or load (light bulb)
Conductors (wire)
5
Q
- What represents capacitance in an AC circuit?
A
A capacitor (same as a condenser)
6
Q
- What is the function of a capacitor?
A
To store electricity
7
Q
- What is the unit of measure for capacitance?
A
Farad
8
Q
- What is the standard unit of measure for frequency?
A
Hertz
9
Q
- What is the basic component that only allows current to flow in one direction?
A
Diode (acts like a check valve)
10
Q
- What is inductance?
A
Voltage induced by magnetic flux lines in a coil in an AC circuit.
11
Q
- What is an example of an inductor in a magneto?
A
The coil
12
Q
- What is impedance?
A
Total opposition for AC to flow due to
resistance,
inductive reaction,
capacitive reactance
13
Q
- What causes opposition to the flow of current in an AC circuit?
A
Inductive & capacitance reactance
14
Q
- What is the unit of measurement for impedance?
A
Ohms
15
Q
- What is the general purpose of a resistor?
A
To limit current
16
Q
- How may the value of a small, fixed resistor be determined?
A
By the color bands on the resistor
17
Q
- What are two things that happen when current flows through a conductor?
A
A magnetic field is generated, and the conductor heats up
18
Q
- What is the common name for the lines of force that make up a filed surrounding a magnet?
A
Magnetic flux lines
19
Q
- What is the concept that describes the relationship between electricity and magnetism?
A
Electromagnetism
20
Q
- What are the four factors that affect the resistance of an electrical conductor?
A
wire gauge,
length,
temperature,
material
21
Q
- What is the unit of measurement of power in a DC circuit?
A
Watt
22
Q
- What is a kilowatt?
A
1,000 watts
23
Q
- In a DC circuit, what occurs when voltage is increased while resistance remains constant?
A
increase in current
24
Q
- What are the three types of DC electrical circuits?
A
Series
Parallel
Complex (series & parallel)
25
25. A 24-volt lead-acid batter has how many cells?
12 cells, each are 2 volts
26
26. What are the units that a battery capacity is measure in?
Ampere-hours
27
27. What should be the specific gravity of the electrolyte in a fully charged lead acid battery?
Between 1.275 - 1.300
28
28. What instrument is used to determine the specific gravity of electrolyte in a lead acid battery?
a hydrometer
29
29. Why can a hydrometer NOT be used to determine the charge of a nickel-cadmium battery?
Specific gravity of the electrolyte in a nickel-cadmium battery does not change during charge or discharge.
30
30. When using a hydrometer to check the charge of a lead-acid battery, at what temperatures must a correction factor be applied to the reading?
Adjustments must be made if temperature of the electrolyte is above 90 or below 70 degrees F
31
31. What is electromagnetic induction?
the transfer of electrical energy by means of a magnetic field (lines of flux).
32
32. How are battery compartments protected against corrosion?
They are coated with special corrosion resistant paint
33
33. What should be the correct electrolyte level in a properly serviced battery?
approx. 3/8 inches above the plates
34
34. What are paralleling generators and how is the load distributed?
two or more generators supply power for a load that must be shared equally.
35
35. Describe a no-trip circuit breaker (trip free).
A “trip free” breaker makes it impossible to manually hold the circuit closed when excessive current is flowing. (It pops when circuit gets hot and can’t be reset until it has cooled off).
36
36. Can you store Ni-cad and lead-acid batteries together?
No, fumes from the lead-acid battery can contaminate the Ni-cad battery.
37
37. What is the result of an imbalanced cell in a nickel-cadmium battery?
current will increase across the cell, causing it to heat up.
38
38. What happens to the specific gravity of the electrolyte in a lead-acid battery when temperature changes?
specific gravity will vary with temperature variations.
39
39. What is a L.E.D.?
Light Emitting Diode
40
40. What is S.L.A. Battery?
Sealed Lead Acid Battery
41
41. What is the basic unit of measure for inductance?
Henry
42
42. What prevents reverse current flow in a DC Alternator?
Reverse current cutout
43
43. How many wires may be a installed on a single terminal lug?
Four
44
44. How do you identify wire types?
Lettering in the insulation
45
45. Name some functions of a multimeter
Voltage(volts)
Current(amps)
Resistance(ohms)
46
46. Name two types of resistors.
Variable & fixed
