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General A&P FAA > Basic Electricity > Flashcards

Basic Electricity Flashcards

1
Q

What constitutes a capacitor

A

two conductors separated by an insulator

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2
Q

What is the purpose of a capacitor

A

It stores electrical energy in electrostatic fields

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3
Q

Does a capacitor in an AC circuit cause the current to lead or lag the voltage

A

It causes the current to lead the voltage

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4
Q

The basic unit of a capacitor

A

The farad

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5
Q

The reason why an electrolytic capacitor can only be used in a DC circuit and not an AC circuit.

A

They are polarized so they can only work in one direction. If current passes in the opposite direction, it will pass through the capacitor and overheat it (explode)

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6
Q

What is meant by inductuance

A

The ability to store electrical energy in electromagnetic fields

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7
Q

The basic unit of inductance

A

The henry

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8
Q

What is an example of an inductor used in a magneto

A

The primary and secondary coils

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9
Q

Does an inductor in an AC circuit cause the current to lead or lag the voltage

A

lags

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10
Q

How can you find the polarity of an electromagnet

A

Hold the electromagnet in your left hand with your fingers encircling the coil int he direction electrons flow (from negative to positive). Your thumb will point to the north pole

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11
Q

What is meant by impedance

A

Total opposition to current flow in an AC circuit. The vector sum of capacitive and inductive reactance and resistance

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12
Q

What is the basic unit of impedance

A

Ohm

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13
Q

What are 5 sources of electrical energy

A
  1. Light
  2. Radiation
  3. Chemical
  4. Magnetism
  5. Heat
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14
Q

What is the basic unit of power in a DC circuit

A

The watt

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15
Q

What is meant by a megawatt

A

1,000,000 watts

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16
Q

What is the formula for power in a DC circuit

A

P=IV

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17
Q

The relationship between mechanical and electrical power

A

1 horsepower= 746 watts

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18
Q

What is meant by true power in an AC circuit

A

The actual amount of power being used, or dissipated, in a circuit

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19
Q

In what unit is true power expressed in

A

Watt

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20
Q

What is meant by apparent power in an AC circuit

A

The combination of reactive power and true power is called apparent power, and it is the product of a circuit’s voltage and current, without reference to phase angle

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21
Q

The basic unit of reactive power

A

VAR (Volt amps reactive)

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22
Q

What is meant by power factor in an AC circuit

A

The ratio of true power to apparent power or the ratio of circuit resistance to circuit impedance

23
Q

What 2 things happen when current flows through a conductor

A
  1. Heat is generated

2. Magnetic field surrounds the conductor

24
Q

The 4 factors that affect resistance of a conductor

A
  1. Temperature
  2. Length
  3. Cross sectional area
  4. Material
25
Q

What is meant by continuity in an electrical circuit

A

The circuit is continuous so electrons can flow from one terminal to the next

26
Q

The 3 things that an electrical circuit must have in order to work

A
  1. Supply voltage
  2. Consumers
  3. Conductors to join the consumers to the supply
27
Q

What would happen to the current in a DC circuit if length of the conductor doubled but all other factors remained the same?

A

The current would decrease by half

28
Q

What is meant by the capacity rating of a lead-acid battery?

A

The number of hours a battery can supply a given current flow

29
Q

What is the unit that a battery capacity is expressed in

A

Ampere-hours

30
Q

What electrolyte is used in a lead acid battery

A

Sulfuric acid and water

31
Q

Does the specific gravity of the electrolyte in a lead-acid battery increase or decrease as the battery becomes discharged

A

Decreases

32
Q

What is the specific gravity of a fully charged lead-acid battery?

A

1.275 - 1.300

33
Q

How many cells are there in a 24-volt lead acid battery

A

12

34
Q

What is the range of temperature of the electrolyte in a lead acid battery that does not require a correction when measuring its specific gravity

A

70-90F

35
Q

What instrument is used to measure the specific gravity of the electrolyte in a lead acid battery

A

A hydrometer

36
Q

How doe you treat a lead acid battery compartment to protect it from corrosion

A

paint it with asphaltic paint or polyurethane enamel

37
Q

What is used to to neutralize spilled electrolyte from a lead-acid battery?

A

mixture of sodium bicarbonate and water

38
Q

Why is the closed-circuit voltage of a lead acid battery lower than its open circuit voltage

A

There is a voltage drop across the battery

39
Q

What is the open-circuit voltage of a lead acid cell

A

2.1 volts

40
Q

What gases are released when a lead acid battery is being charged?

A

hydrogen and oxygen

41
Q

What precautions should be taken in the maintenance shop where both lead acid and nickel-cadmium batteries are serviced?

A

They should be kept separate and tools for servicing them should be kept separate

42
Q

What is the electrolyte used in a nickel-cadmium battery

A

Potassium hydroxide and water

43
Q

Why is a hydrometer not used to measure the state of charge of a nickel-cadmium battery?

A

The SPG does not change since there are no chemical changes that occur when the battery is being discharged or charged

44
Q

The lowest level of electrolyte in a nickel-cadmium battery occurs when

A

when the battery is fully discharged

45
Q

What is the result of cell imbalance in a nickel-cadmium battery?

A

Low internal resistance which leads to higher current flow between the unbalanced cells which leads to high heat

46
Q

What is thermal runaway?

A

Low internal resistance increase the rate of internal heat generation exceeds the rate at which the heat can be expelled. The battery temperature increase until the cells dry out and the container softens, breaks and melts.

47
Q

How can thermal runaway be prevented?

A

Carefully monitor the temperature of the middle cells and controlling the charging current

48
Q

How is it possible to know when a nickel-cadmium battery is fully charged?

A

Completely discharge the battery and give it a constant-current charge to 140% of its ampere-hour capacity

49
Q

What is used to neutralize spilled electrolyte from a nickel-cadmium battery?

A

Solution of boric acid and water

50
Q

EMF is measured in what?

A

Volts

51
Q

What are the 3 effects of electrical current?

A
  1. Heating effect
  2. Magnetic effect
  3. Chemical effect
52
Q

4 factors affecting electrical resistance

A
  1. Length of wire
  2. Type of material
  3. Cross section
  4. Temperature
53
Q

Kirchoff’s First Law states:

A

Total current flow into one point on a circuit, is equal to the current flow out of that point

54
Q

Kirchoff’s Second Law states:

A

If all voltage drops in a closed circuit are added up, the sum equals the total applied voltage

General A&P FAA (26 decks)

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