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1st 6 > PHEP Chapter 1 & 3 > Flashcards

PHEP Chapter 1 & 3 Flashcards

1
Q

A coil is said to be saturated when…?

A

Large changes in current cannot increase the flux

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2
Q

What is the stability of a resistor?

A

Property of maintaining a small tolerance under all conditions

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3
Q

Power rating of motors/working equipment is mostly based on what?

A

Power they can use to do mechanical work

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4
Q

If negative terminal of battery is connected to positive terminal of another battery these batteries are connected in what manner?

A

Series

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5
Q

Voltage is additive in what type of circuit?

A

Series

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6
Q

When will power sources oppose each other?

A

When connected in a way in which their polarities are not in the same direction

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7
Q

The voltage drop equals…?

A

The source voltage

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8
Q

In a series circuit, current flow from …?

A

Negative terminal through circuit to positive terminal

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9
Q

What does the electromagnetic circuit breaker use?

A

Principle of magnetism to open a circuit

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10
Q

Total current in a parallel circuit can be found by …?

A

Adding all branch currents

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11
Q

The reciprocal method can be used to calculate …?

A

Total resistance of any combination of parallel resistances

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12
Q

What does Kirchoff’s first loaw state?

A

Sum of voltage drops around any closed loop is equal to sum of the EMF’s in that loop

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13
Q

Resistor failures are usually the result of ..?

A

Heat generated in the resistor by a current

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14
Q

Heat loss if electric transmission is directly proportional to …?

A

Resistance

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15
Q

True or False: DC sent of long distances have large power loss

A

True

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16
Q

What do transformers do?

A

Convert AC from one combination of voltage/current to another

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17
Q

AC power sources are called?

A

AC generators or alternators

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18
Q

What type of power source uses physical motion and magnetism to produce an AC voltage?

A

Generators

19
Q

What is angular motion?

A

Motion in a circle

20
Q

What does a waveform show?

A

Magnitude and direction of current or voltage at every instant of time

21
Q

What is magnitude of current directly proportional to?

A

Magnitude of voltage

22
Q

What is the skin effect?

A

Higher concentration of current near conductor surface

23
Q

What is an electric current made of?

A

Many free electrons moving in the same direction in a wire

24
Q

What is the magnitude of the induced EMF directly proportional to?

A

Strength of magnetic field, length of conductor, speed at which conductor moves through magnetic field

25
Q

Strength and direction of magnetic field around a conductor depends upon…?

A

Magnitude and direction of current

26
Q

What determines the magnitude of the self induced EMF?

A

Frequency of an AC current and its amplitude

27
Q

What type of conductor creates a greater back EMF?

A

A coil conductor

28
Q

What cuts the conductor at more than one point?

A

Flux lines

29
Q

What does inductance do in an electrical circuit?

A

Opposes any change in current

30
Q

What are the units of inductance?

A

Henrys

31
Q

Inductors are sometimes called …?

A

Chokes or coils

32
Q

How many degrees of of phase is the secondary current in relation to the primary curent?

A

180 degres

33
Q

What are the units of capacitance?

A

Farads

34
Q

True or False: Sine wave of a DC current is both above and below the horizontal axis

A

False

35
Q

What is a cycle?

A

360 degree or one complete sine wave

36
Q

At what point are current and voltage in phase?

A

When they both reach their maximum and minimum at the same time

37
Q

What is the amplitude of an AC current or voltage?

A

Maximum value that the current or voltage reaches

38
Q

What is used to indicate time relationships?

A

Phase

39
Q

What is frequency?

A

Number of cycles generated in one second

40
Q

Does a capacitor’s current lead or lag the applied voltage?

A

Leads by 90 degrees

41
Q

True or False: In a purely resistive circuit the apparent power is equal to the true power

A

True

42
Q

What s the E-I phase angle in a purely resistive circuit

A

Zero

43
Q

In a purely inductive circuit the applied voltage leads the current by… ?

A

90 degrees

44
Q

In a purely capacitive circuit the current leads the applied voltage by …?

A

90 degrees

1st 6 (13 decks)

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