Deck 19: Capacitive Circuits

Question 1

Instead of combining waveforms that are out of phase, they can be added more quickly by using their equivalent ______________.

Answer 1

phasors

Question 2

The resultant of the phasor addition of X_C and R is their total opposition in ohms called ______________.

Answer 2

impedance

Question 3

For a series RC circuit, when X_C is equal to or greater than 10 times R, Z_T is approximately _________ X_C.

Answer 3

equal to

Question 4

A practical application for a phase-shifter circuit is to provide a voltage of ______________ phase to set the conduction time of semiconductors in power-control circuits.

Question 5

A series circuit has different voltage drops but one common ______________.

Question 6

When branch currents are out of phase are combined, they cannot be added without taking the phase ______________ into account.

Question 7

A ______________ capacitor's low reactance allows developing all the ac signal voltage of the generator across R.

Question 8

When capacitors are connected in series across a voltage source, the series capacitors serve as a voltage ______________.

Question 9

When voltages are out of phase with each other, arithmetic addition is not possible and ______________ (or algebraic) addition becomes necessary.

Question 10

The (number only) ______________ degree phase angle results because i_c depends on the rate of change of v_c.

Question 11

The resultant of the phasor addition of X_C and R is their total opposition in ohms, called

A) reactance
B) reluctance
C) resistance
D) impedance

Question 12

In a series RC circuit, the phasor for X_C, IX_C, or V_C is at

A) 0°
B) 45°
C) 90°
D) ?90°

Question 13

The trigonometric function of an angle equal to the ratio of the opposite side to the adjacent side of a triangle is the

A) sine
B) cosine
C) tangent
D) cotangent

Question 14

For a series RC circuit, when R is equal to or greater than 10 times X_C,

A) Z_T is approximately equal to R
B) Z_T is approximately equal to C
C) Z_T is equal to ??
D) Z_T is equal to 0 ?

Question 15

What circuit can be used to set the conduction time of semiconductors in power-control circuits?

A) RC filter
B) Oscillator
C) Regulator
D) Phase-shifter

Question 16

What circuit has different branch currents but one common voltage?

A) Amplifier
B) Bridge
C) Series
D) Parallel

Question 17

When branch currents that are out of phase are combined

A) they are simply added
B) they are simply subtracted
C) they are added taking phase difference into account
D) the resultant is zero

Question 18

For R in parallel with X_C, Z_EQ can be calculated

A) by adding R and X_C
B) by using product over algebraic sum
C) by subtracting R and X_C
D) by using Ohm's law

Question 19

For a parallel RC circuit, when X_C is equal to or greater than 10 times R

A) Z_EQ is approximately equal to R
B) Z_EQ is approximately equal to X_C
C) ZEQ is approximately 0 ?
D) Z_EQ is approximately ??

Question 20

What is the total current when a 30mA I_R is in parallel with another branch current of 40 mA for I_C?

A) 5 mA
B) 50 mA
C) 500 mA
D) 70 mA

Question 21

In order for a coupling capacitor to be effective, its reactance should be

A) 1/2 of the series resistor
B) 1/3 of the series resistor
C) 1/5 of the series resistor
D) 1/10 or less of the series resistor

Question 22

What value of capacitance can be used as a coupling capacitor for frequencies 50 Hz and up with a series resistance of 400 ??

A) 0.79 ?F
B) 7.9 ?F
C) 79 ?F
D) 790 ?F

Question 23

When capacitors are connected in series across a voltage source, the series capacitors serve as a

A) coupling capacitor network
B) voltage divider
C) filter
D) voltage tripler

Question 24

When voltages are out of phase

A) arithmetic addition can be used
B) phasor addition is not possible
C) they cannot be combined by any means
D) phasor addition is necessary

Question 25

With sine-wave alternating current, the voltage division between series capacitors can be calculated on the basis of

A) resistance
B) conductance
C) reactance
D) impedance

Question 26

For a capacitor, the value of charge or discharge current is zero when

A) the capacitance is low
B) the capacitive reactance is high
C) d_v/d_t is a constant
D) d_v/d_t is zero

Question 27

When calculating capacitive current, capacitive reactance applies

A) only to sine waves
B) only to square waves
C) only to pulse waves
D) to any nonsinusoidal waveform

Question 28

If capacitance is increased and higher frequency sine-wave voltages are applied

A) X_C increases
B) X_C decreases
C) X_C remains unchanged
D) I_C decreases

Question 29

For any capacitor, what is the phase relationship between v_c and i_c for all values of capacitance or any frequency of sine wave alternating voltage?

A) 45°
B) 90°
C) -90°
D) -45°

Question 30

In what circuit is i_c used as a reference and v_c is considered to lag by 90°?

A) Series resistive
B) Series capacitive
C) Parallel resistive
D) Parallel capacitive

Question 31

When a capacitor and resistor are connected in series, the current is limited by

A) X_C only
B) R only
C) both X_C and R
D) neither R nor X_C

Question 32

When analyzing an RC circuit, which of the following values of I and V can be used?

A) rms only
B) Peak only
C) Instantaneous only
D) rms, peak, or instantaneous

Question 33

In a series RC circuit, V_R and I are

A) in phase
B) out of phase by 45°
C) out of phase by 90°
D) out of phase by -90°

Question 34

Which law or theorem states that the hypotenuse is equal to the square root of the sum of the squares of the sides?

A) Thevenin
B) Kirchhoff
C) Pythagorean
D) Norton

Question 35

Capacitive reactance decreases with more capacitance and higher frequencies for sine-wave ac voltage applied.

Question 36

The opposition that resistance offers remains the same for dc and ac circuits.

Question 37

A coupling capacitor is used to pass the desired ac signal variations while blocking the steady dc level of a fluctuating dc voltage.

Question 38

For any capacitor, the 180° phase relationship between v_c and i_c exists for all values of capacitance or any frequency of sine wave alternating voltage.

Question 39

In series circuits, the current i_c is the reference, and then the voltage v_c can be considered to lag i_c by 90°.

Question 40

The 90° phase angle results because i_c depends on the rate of change of v_c.

Question 41

Capacitive current is the same in all parts of a series circuit.

Question 42

With respect to a series current, both the applied voltage and capacitive voltage are 180° out of phase with capacitive current.

Question 43

Although capacitive voltage lags capacitive current by 90°, both waves have the same frequency.

Question 44

When a capacitor and a resistor are connected in series, the current is the same in both X_C and R.

Question 45

Circuit values of I and V may be in rms, peak, peak-to-peak, or instantaneous, as long as the same measure is applied to the entire circuit.

Question 46

When series voltage drops that are out of phase are combined, they can be added without taking the phase difference into account.

Question 47

Instead of combining waveforms that are out of phase, they can be added more quickly by using their equivalent phasors.

Question 48

The Pythagorean theorem states that the hypotenuse is equal to sum of the squares of the sides.

Question 49

In a series RC circuit, V_T is the phasor sum of the two voltages V_R and V_C 90° out of phase.