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2nd year- Test 3 > A.C. Systems- Lesson #6: Understanding the Basic Characteristics of AC Circuits > Flashcards

A.C. Systems- Lesson #6: Understanding the Basic Characteristics of AC Circuits Flashcards

1
Q

True or False?
When a steady direct current flows through a coil, the only opposition to the flow of current is the resistance of the wire from which the coil is made.

A

True

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2
Q

True or False?
Alternating current flowing through a coil is opposed by two factors, resistance (R) and inductive reactance (XL).

A

True

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3
Q

? is the induction of voltage or CEMF that opposes the current flow in a coil.

A

Inductive reactance

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4
Q

Inductive reactance

A

? is the induction of voltage or CEMF that opposes the current flow in a coil.

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5
Q

True or False?
The total current-limiting effect of the inductor is a combination of the inductive reactance and resistance of the inductor.

A

True

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6
Q

The total current-limiting effect of an inductor is called ? and is symbolized by the letter ? .

A

impedance / Z

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7
Q

The total current-limiting effect of an inductor is called ?

A

impedance

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8
Q

impedance

A

The total current-limiting effect of an inductor

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9
Q

symbol by the letter for impedance is?

A

Z

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10
Q

equation for determining the total impedance in an inductive and resistive circuit.

A
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11
Q
A
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12
Q

Study questions 7-8

A

study math

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13
Q

waveform correctly show current and voltage to be “in-phase”?

A
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14
Q

In most AC circuits, the current and voltage are ? .

A

out-of-phase

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15
Q

These sine waves indicate voltage and current ? out-of-phase.

A

45°

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16
Q

True or false?
There can be a phase difference between voltage and current in DC circuits.

A

True

17
Q

The equation for finding power in a circuit when the current and voltage are known is ? .

A

P = E x I

18
Q

Study 14

A

study

19
Q

In a pure resistive circuit, the true power (or watts) is equal to the product of the ? and ? .

A

current / voltage

20
Q

An electrical measurement called VARs is used to measure ? power.

A

reactive

21
Q

An electrical measurement called ? is used to measure reactive power.

A

VAR

22
Q

VARs are equal to the amount of current flowing through a(n) ? part of a circuit times the voltage applied to the ? part of the circuit.

A

inductive / inductive

23
Q

? power in a circuit is the voltage at a certain instant multiplied by the current at that same instant.

A

Instantaneous

24
Q

Instantaneous power in a circuit is ?

A

the voltage at a certain instant multiplied by the current at that same instant.

25
Q

In an AC circuit, when both the current and voltage of the circuit have a negative value, the power of this circuit is ? .

A

Positive

26
Q

In an AC circuit, when both the current and voltage of the circuit have a positive value, the power of this circuit is ? .

A

Positive

27
Q

In an AC circuit, when current of the circuit is ? and the voltage of the circuit is negative, the power of this circuit has a negative value.

A

Positive

28
Q

In an AC circuit, when the current of the circuit is negative and the voltage of the circuit is zero, the power of this circuit has a ? value.

A

zero

29
Q

When the current and voltage are ? , one may be positive while the other is negative.

A

out-of-phase

30
Q

When the current and voltage on a circuit reach maximum values at the same time, power is at its ? possible value. This happens when current and voltage are ? .

A

maximum / in-phase

31
Q

When the current and voltage are ? out-of-phase, the power consumed is zero watts.

A

90°

32
Q

What happens when the current and voltage are 90° out-of-phase?

A

The power consumed is zero watts

33
Q

True or False?
It is theoretically possible for a circuit to be energized at 240 volts and have 100 amperes flowing and yet consume no power.

A

True

Note: Yes, if the circuit was supplying a perfect inductor, no power would be consumed. This situation does not exist in practice because all conductors and coil windings contain some resistance.

34
Q

Study 25

A

Study

35
Q

Power factor is a numeric ratio applied to the ? power to yield the ? power.

A

apparent, true

36
Q

Power factor is the ? of angle Ө in the impedance triangle.

A

cosine

37
Q

True or False?
The power formula P = E x I applies in all cases.

A

False

Note: This applies only in DC circuits and AC circuits when the current and voltage are in-phase, or in a purely resistive circuit where there is no reactive power. Reactive power can be calculated by the formula:

VARs = EL x IL

In a circuit containing reactance, true power can be calculated by the formula:

P = E x I x PF

38
Q

The true power, in watts, consumed by the circuit is consumed by the ? of the circuit.

A

resistance

2nd year- Test 3 (11 decks)

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