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General > Electricity Oral 2 > Flashcards

Electricity Oral 2 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

Storing electrical energy in an electrostatic field

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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

What is the basic unit of capacitance?

A

A farad (F)

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5
Q

Why should electrolytic capacitors not be used in an AC circuit?

A

They are polarized, it will pass current of one polarity but will block current of the opposite polarity

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6
Q

What is meant by inductance?

A

The ability to store electrical energy in electromagnetic fields

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7
Q

What is the basic unit of inductance?

A

Henry

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8
Q

What is an example of an inductor used in a magneto?

A

The coil

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9
Q

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

A

It causes the current to lag behind the voltage

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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 in the direction electrons flow (from negative to positive). Your thumb will point to the north pole of the electromagnet

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11
Q

What is meant by impedance?

A

The total opposition to the flow of AC. It is the vector sum of resistance, capacitive reactance, and inductive reactance

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12
Q

In what units is impedance measured?

A

Ohms

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13
Q

What are five sources of electrical energy?

A

Magnetism, chemical energy, heat, light and pressure.

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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 kilowatt?

A

1,000 Watts

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16
Q

What is meant by a megawatt?

A

1,000,000 Watts

17
Q

What is the formula for power in a DC circuit?

A

Power = Voltage times current (P=E x I )

18
Q

What is the relationship between mechanical and electrical power?

A

1 horsepower = 746 watts

19
Q

What is meant by true power in an AC circuit?

A

The product of the circuit voltage and the current that is in phase with this voltage

20
Q

In what units is true power expressed?

A

Watts

21
Q

What is meant by apparent power in an AC circuit?

A

The product of the circuit voltage and the circuit current

22
Q

In what units is apparent power expressed?

A

In volt-amps reactive (VAR) or kilovolt-amps reactive (KVAR)

23
Q

What is meant by reactive power in an AC circuit?

A

The power consumed in the inductive and capacitive reactances in an AC circuit. Reactive power is also called wattless power

24
Q

In what units is reactive power expressed?

A

In volt-amps reactive (VAR), or (kilovolt-amps reactive (KVAR)

25
Q

What is meant by power factor in an AC circuit?

A

The ratio of true power to apparent power. It is also the ratio of circuit resistance to circuit impedance.

General (19 decks)

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