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Electrical Fundamentals > Week #3 > Flashcards

Week #3 Flashcards

1
Q

What are the two commonly performed functions of a resistor in an electrical circuit?

A

Limit the flow of current throughout the circuit and voltage divider

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2
Q

What is a voltage divider?

A

Any voltage can be obtained

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3
Q

What is the general voltage divider formula?

A

I = E/R

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4
Q

When using resistors of a proper value, for the purpose of greeting, a voltage can almost enable voltage desire be obtained

A

Yes

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5
Q

When there is no resistor in a circuit and unlimited current is allowed to flow this is known as what

A

Ideally, if there is no resistance ,i.e, short circuit is connected across an dc source, infinite current will flow as I=V/R, and R=0. 2.

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6
Q

A resistor that has only one resistance value that cannot be charged or adjusted is known as what type of resistor

A

A fixed resistor

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7
Q

What is one of the most common type of fix resistors?

A

Composition carbon resistor

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8
Q

What are the composite carbon resistor composed of?

A

Compounds of carbon graphite, and a resin bonding material

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9
Q

What determines the value of the resistor?

A

The proportions of carbon and risen material determines the value of resistance

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10
Q

Why are carbon resistors popular?

A

Inexpensive and readily available

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11
Q

The larger the diameter of the resistor indicates what with regards to its power rating

A

Greater Watts

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12
Q

What happens to carbon resistors as they age or if they get over heated

A

The increase instead of decrease in value

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13
Q

A resistor with a tolerance range of 20% 10% or 5% is what type

A

Metal film resistors

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14
Q

A register with the tolerance range of 2% to one percent is what type

A

Wire around resistors?

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15
Q

How are wire round resistors made?

A

By winding a piece of resistance wire around a ceramic core

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16
Q

The resistance of a wire around resistor is determined by what three
Factors

A

The type of material used to make the resistance wire, the diameter of the wire, and the length of the wire

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17
Q

What advantage is there to use a wire round type of resistor?

A

For high power rating ii can operate at higher temperatures

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18
Q

What is used as a visual aid to determine the value of resistor?

A

Colour code

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19
Q

Does each colour represent a number value when using the colour code to determine the value of a resistor?

A

Yes

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20
Q

How many colour bands can resistors

A

3 to 5

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21
Q

A resistor with only three colour bands will have tolerance of what

A

Plus or -20%

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22
Q

The third band in a five band resistor does what function

A

Number value

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23
Q

What does the tolerance band actually indicate?

A

The range of resistance plus or minus the tolerance colour indicate

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24
Q

Ask Jeff, the saying he uses to remember the colour code chart

A

Bad beer, rots our young guts, but vodka goes well

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25
Q

Why should we not exceed the power rating of a resistor?

A

The resistor will be damaged

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26
Q

A resistor that can change or very its resistance over a specific range of resistance is known as what

A

A variable resistor

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27
Q

How do variable resistors generally work?

A

The value of resistance can be adjusted between one end of the resistive wire and sliding tab

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28
Q

What are the two most common types of variable resistors?

A

Wire around variable resistors and multiturn variable resistor

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29
Q

What does the acronym MM stand for?

A

Multimeter

30
Q

A MM that uses a pointer and a scale to indicate the tested value is known as what type of metre

A

Analogue metres

31
Q

What type of movement is used in the analog metre shown

A

Movement-coil meter

32
Q

Another type of metre movement that allow analog metres to which use is a magnetic field and either attracts or repel the iron vanes, which are attached to the pointer is known as what

A

Gelvanometers

33
Q

How does an analog metre work?

A

Magnetic poles repel each other

34
Q

What type of MM do we get with our tool kids?

A

Digital multimeter

35
Q

How does a digital MM work?

A

Putting the black pin on common and red on hot, selecting the dial to the right unit and reading the measurements on the screen

36
Q

Are all MM accurate?

A

No

37
Q

When taking a measurement, is it important to select the correct scale pro placement and correct symbol on the selector switch

A

Yes

38
Q

Is human error and metre failure a dangerous issue?

A

Yes

39
Q

Is human error and metre failure a dangerous issue?

A

Yes

40
Q

How does an MM measure voltage in AC or DC circuits?

A

By connecting the prong to any part of the circuit

41
Q

How does Emma measure current not clamped on an AC or DC circuit?

A

It must let the current flow through the circuit, so basically unconnected the circuit and connect with the multimeter until the circuit works again

42
Q

Can you use a clamp on MM to measure current in an AC circuit and why

A

No cause it will blow a fuse on your multimeter

43
Q

Can you use a clamp on MM to measure current in a DC circuit?

A

No cause it will blow a fuse on your MM

44
Q

A lower resistance device that conducts most of the circuit DC current away from the metre movement which then lasts 1 m³ movement to read multiple currents is known as what

A

Ammetre shunts

45
Q

Do multiple range DC and metres use multiple shunts

A

Yes

46
Q

Can you build your own DC shunt using a resistor and ohms law?

A

Yes

47
Q

What is the formula for calculating the resistor values for an Aytron shunt?

A

Rs = Im X Rm/ It
RS equals resistance of the shunts I am equals current of the metre movement RM equals resistance of the metre movement IT equals total circuit current

48
Q

What is the purpose of using a shunt in an AC ammeter?

A

To increase the range, but cannot be used to decrease the range

49
Q

A advice that uses two sets of Winings primary and secondary that are close in proximity that depending on the number of turns can increase or decrease the voltage utilizing a magnetic field is known as what

A

Current transformer

50
Q

A CT or current transformer is a single set of winding much like the secondary windings of a standard transformer what purpose of a CT

A

When a large amount of AC must be measured, a different type of current transformer is connected in the powerline

51
Q

What enables a CT to be able to be utilized from a very high current situation right down to the very small current situation

A

The turn ratio of the transformer can be changed by looping. The power wire through the opening in the transformer, a primary winding of more than one turn.

52
Q

What is an ohmmeter?

A

The ohmmeter is used to measure resistance

53
Q

Can we use an old metre when the circuit is energized?

A

Yes

54
Q

Do the MM that come with the tool kits have the ability to measure multiple ranges of the following voltage, AC and DC resistance and capacity

A

Yes

55
Q

Can we measure power of watts with a MM from the tool kit?

A

No, we must find power with ohms law by measuring resistance X volt

56
Q

If you wanted to know how much power or watts a circuit was using what must we do?

A

Use law and find amperage voltage or resistance

57
Q

Can you purchase a wattmeter?

A

Yes but expensive

58
Q

What are the two basic types of wattmeter?

A

Electrodynamicmetre wattmetre and induction watt metre

59
Q

A device that uses an X and a Y axis to visually display any electoral waveform is known as what

A

Oscilloscopes

60
Q

The X axis on the oscilloscope represents what with regards to the waveform

A

Time

61
Q

DY axis on an oscilloscope represent what with regards to the waveform

A

Voltage

62
Q

When looking at an AC waveform, what is VPN RMS value?

A

VP equals peak voltage RMS equals root mean square

63
Q

How do we calculate the frequency f measured in hertz of an AC waveform

A

f=z/t

64
Q

Any equation answered above what is base unit of measurement required for time?

A

Seconds or microseconds

65
Q

What is the formula for calculating tea or period of a weight form and what unit of measurements is used for Period.

A

period = 1/frequency
T = periods

66
Q

We can calculate an amplitude by using 1/2 of the distance between the crest, positive peak and through negative peak so if the waveform is centred on the horizontal axis of the cell and the peak is five, which is one volt increments above the axis and through is 51 V increments below the axe the total distance would be 10 in increments so what would be a or amplitude of the waveform be

A

50A

67
Q

What formula do we use to calculate the velocity v of a waveform using frequency f and wavelength?

A

v= f X ^

68
Q

A wavelength unit of measurement is in what

A

Meter

69
Q

When shown on the board wavelength and period are indicate to be the same measurement but what is the main difference?

A

Wavelength is the distance between two identical points in the cycle of a wave. Period Is the time it takes to complete one cycle of the wave?

70
Q

What is a Megger?

A

To measure insulation resistance

71
Q

How does megger work?

A

It applies a high voltage to the current and measures the amount of current that flows through the insulation

72
Q

List the two types of megger that are listed in the book

A

Electronic type and portable type

Electrical Fundamentals (4 decks)

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