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Electrical Exam 1 > Basic Electricity > Flashcards

Basic Electricity Flashcards

1
Q

Name two examples of insulators

A

Mica, glass, wood, rubber

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2
Q

Name two examples of good conductors

A

copper, silver, gold

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3
Q

Name an example of a semi-conductor

A

silicon, germamnium

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4
Q

A good conductor has 1-__ valence electrons

A

1-2

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5
Q

A good insulator has __ valence electrons

A

8

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6
Q

A semi-conductor has __ valence electrons

A

4

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7
Q

one coulomb is 6.25x10 to the power of 18 electrons

A

yes

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8
Q

Ampere is described as one _______ per second

A

coulomb

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9
Q

poles are where the magnetic lines of force enter and leave the _______

A

magnet

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10
Q

The North Pole always points to the ______ pole of the magnetic

A

south

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11
Q

magnetic lines of force always complete ______

A

loops

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12
Q

A ferromagnetic material is any material that behaves like _____ in a magnetic field

A

iron

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13
Q

Flux density - stronger magnetic force means more lines of _____ per area

A

force

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14
Q

Magnetic screen is where magnetic lines of force pass through _______

A

anything

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15
Q

Residual magnetism Is the ability of a material to hold a magnetic _____

A

field

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16
Q

Factors that affect strength of an electromagnet

  1. number of ____
    2, spacing between ____
  2. type of ______ used
  3. amount of _____ flow
A
  1. number of turns
  2. spacing between turns
  3. type of material used
  4. amount of current flow
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17
Q

A screen uses soft iron to shield a device, providing an alternate path for the magnetic ____

A

field

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18
Q

Reluctance is the property that opposes the setting up of ____ lines

A

flux

19
Q

Name three methods of demagnetizing?

A

electrical current

heat

vibration

20
Q

three precautions to avoid damaging magnets

A
  1. do not heat
  2. do not expose to AC
  3. do not expose to vibration
  4. don’t store magnet near another magnet
21
Q

What is a keeper?

A

A soft iron piece placed across poles to provide easy path for flux

22
Q

Low voltage?

A

31v-750v

23
Q

High voltage?

A

751v or more

24
Q

Extra low voltage?

A

30v or less

25
Q

Name two advantages of AC?

A
  1. AC can be stepped up or down

2. alternators can be manufactured with much higher voltage and power ratings

26
Q

What is an alternation?

A

one full wave form

27
Q

Frequency is the number of times per second a _______ repeats itself

A

waveform

28
Q

Peak value is the maximum value or current or voltage in an AC ______

A

waveform

29
Q

Average value is the average value based on ___________ values

A

instantaneous

30
Q

“RMS” means

A

root means square

31
Q

“In phase” is when the voltage wave and current wave reach peak values, and 0 values at ______ point in time

A

same

32
Q

“Out of Phase” is when voltage and current wave reach peak values, and 0 values at ______ points in time

A

different

33
Q

Phase angle is the difference in _______ between one phase, or value and another

A

degrees

34
Q

Name four factors affecting inductance

A
  1. number of turns
  2. coil diameter
  3. length of the coil
  4. core material
35
Q

A Henry describes the amount of resistance in an _______ load

A

inductive

36
Q

Farad is the basic unit of ________ where one coulomb of charge for 1 second yields a potential difference of 1 volt

A

capacitance

37
Q

capacitors can _____ voltage to increase motor efficiency

A

slow

38
Q

“ICE’ means current in a capacitive circuit slows ______

A

voltage

39
Q

In a resistive circuit voltage and current are in _____

A

phase

40
Q

In an inductive circuit the current lags voltage by ____ degrees

A

90

41
Q

In a capacity circuit the current leads voltage by ___ degrees

A

90

42
Q

Name three reasons for power loss in transformers

A
  1. resistance in the windings
  2. hysteresis
  3. eddy currents
43
Q

electrical equipment voltage imbalance must be within __%

A

2%

44
Q

electrical equipment current imbalance must be within __%

A

10%

Electrical Exam 1 (2 decks)

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