RLC Flashcards

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1
Q

Inductance opposes a change in _____

A

Current

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2
Q

Inductance of a coil is not effected by the _____

A

Frequency of applied voltage

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3
Q

To find inductive reactance of a circuit you must know _____ and ______

A

Frequency and inductance

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4
Q

There is no phase difference between current and voltage across ____
A. Inductor
B. Resistor

A

Resistor

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5
Q

Capacitance opposes the change in _____

A

Voltage

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6
Q

In series RC, the voltage across the resistor is in phase with the current, true or false?

A

True

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7
Q

If a series is resonant, circuit impedance is equal to _____

A

Circuit resistance

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8
Q

Capacitors in parallel add _____

A

Directly.

C1 + C2 + C3

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9
Q

Capacitors in series add _____

A

Inversely

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10
Q

When a circuit is pure resistance the PF is _____

A

1

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11
Q

In a parallel resonant circuit the impedance is at a _____ and line current is at a _____

A

Maximum, minimum

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12
Q

In a series resonant circuit the impedance is at a _____

A

Minimum

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13
Q

When frequency of an inductive circuit increases, the current ______

A

Decreases

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14
Q

In AC capacitance, the current varies directly with the _____

A

Frequency

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15
Q

XL =

A

2pi • f • L

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16
Q

L=

A

XL / 2pi • f

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17
Q

Q factor =

A

XL / R

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18
Q

R = Esquared / P

Transpose

A

P = E squared / R
P = I squared / R

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19
Q

Fr =

A

1 / 2pi • square root LC

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20
Q

When comparing DC and AC circuits, the DC value will always be what part of the vector?

A

X axis (resistance)

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21
Q

When comparing DC and AC circuits, AC values will always be on what part of the vector?

A

Hypotenuse

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22
Q

Two principal parts of a capacitor

A

Plates, dielectric

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23
Q

Two principal parts of an inductor

A

Coil, core

24
Q

There is no inductance in a DC inductive circuit after five time constants. T/F?

A

True.

25
Q

What is the danger of putting an inductor in a DC circuit?

A

The current can be dangerously high

26
Q

What side of impedence triangle is impedance?

A

Hypotenuse

27
Q

What side of impedance triangle is reactance?

A

Opposite

28
Q

What side of impedance triangle is resistance?

A

Adjacent (x axis)

29
Q

Henries add ______ in series

A

Directly

30
Q

Henries add _______ in parallel

A

Inversely

31
Q

Capacitors add _______ in series

A

Inversely

32
Q

Capacitors add ________ in parallel

A

Directly

33
Q

In induction any change in current means change in flux. T/F?

A

True

34
Q

Inductance is the property of a circuit that opposes any change in current in that circuit. What does this mean for current?

A

If current increases, induced EMF will try to push it back down. If current decreases induced EMF will try to push it back up.

35
Q

Induced voltage opposes applied voltage. T/F?

A

True.

36
Q

A voltage is induced across the conductor when ______

A

The magnetic field collapses

37
Q

How do you prevent a dangerous arc at a switch when opening a DC inductor?

A

Free wheeling diode or field discharge resistor

38
Q

How does a free wheeling diode work?

A

Before a free wheeling diode is installed when the switch is opened the inductor will try to maintain current slow causing an arc across the switch. When the FwD is added into the circuit the inductor acts as a source, the polarity of the FWD changes and now current will flow through the diode until all energy is dissipated instead of arching.

39
Q

How to calculate current after ___seconds.

A

I = t • E/L

Ex) I = 10s • 20V/10H = 20A

40
Q

What is the main effect of an inductor in a DC circuit?

A

To slow rate of current rise.

41
Q

What is the formula for tau?

A

L/R

42
Q

Capacitors oppose a change in ______

A

Voltage

43
Q

What will happen to current of a capacitor when source is changed from AC to DC?

A

It will decrease. DC does not change polarities so the capacitor cannot discharge

44
Q

What happens to XL when turns increase?

A

Increases

45
Q

How many decimal places to move for micro farads

A

6

46
Q

In non resonance and resonance do the watts of the resistor change?

A

Yes

47
Q

Formula for L

A

XL / 2pif

Write this down

48
Q

When converting an equation to resonance, which value do you keep?

A

Frequency, resistor resistance

49
Q

When frequency is increased, inductance _______ and capacitance _______

A

Increases, decreases

50
Q

When resistance and inductance is on the same angle, the PF is

A

100%

51
Q

When calculating motor input and output, what is the process of calculating the three values by pf and ef?

A

hp x 746 gets output, divide output by efficiency, that value is watts. Divide watts by power factor, that value is input.

52
Q

Where do you put the value of watts from the motor?

A

Watts calculated from the motor goes on watts of the resistor of the motor when broken down between resistor and inductor.

53
Q

Where do you put the value of input when calculating motor?

A

Input value is the VA of the motor WIRE

54
Q

Where do you find the VaR of the inductor on the motor wire?

A

Input squared minus watts squared

55
Q

When looking at a sine wave, what do the block lines represent?

A

1 alternation

56
Q

How many degrees is 1 alternation?

A

180

57
Q

How do you calculate the angle of a sine wave?

A

Find amount of blocks in 1 alternation.
180/# of blocks = degree of each block. Count blocks between different sine waves and multiple degrees by that amount.