Deck 18: Series Alternating-Current Circuits

Question 1

The load current is in phase with the supply current for __________ loads

A) purely resistive
B) purely capacitive
C) purely inductive

Answer 1

purely resistive

Question 2

The load current lags the supply voltage by 90 degrees for __________ loads

A) purely resistive
B) purely capacitive
C) purely inductive

Answer 2

purely inductive

Question 3

The load current leads the supply voltage by 90 degrees for __________ loads

A) purely resistive
B) purely capacitive
C) purely inductive

Answer 3

purely capacitive

Question 4

The opposition to current offered by a purely-capacitive or a purely-inductive load is termed

A) resistance
B) reactance
C) impedance

Question 5

The inductive reactance of a load is __________ the supply frequency

A) directly-proportional to
B) inversely-proportional to
C) unaffected by

Question 6

The capacitive reactance of a load is __________ the supply frequency

A) directly-proportional to
B) inversely-proportional to
C) unaffected by

Question 7

The inductive reactance of a load is directly-proportional to

A) the supply voltage
B) the supply voltage.
C) its self inductance

Question 8

The capacitive reactance of a load is directly-proportional to

A) the supply voltage
B) the supply voltage.
C) its capacitance

Question 9

The opposition to the drift of current in an inductive-reactive circuit is termed

A) resistance
B) inductive reactance
C) impedance
D) 0

Question 10

The potential-difference across a capacitive-resistive circuit, divided by the load current, is termed

A) resistance
B) capacitive reactance
C) impedance
D) 0

Question 11

The reference phasor in any a.c. circuit is normally drawn along the

A) horizontal positive axis
B) vertical positive axis
C) horizontal negative axis
D) vertical negative axis

Question 12

The reference phasor for a series a.c. circuit is the __________ phasor

A) voltage
B) current
C) resistance
D) reactance

Question 13

Phasors are said to 'rotate'

A) at synchronous speed
B) clockwise
C) counterclockwise

Question 14

The impedance of a load is the __________ sum of the load's resistance and reactance

A) algebraic
B) geometric
C) phasor

Question 15

The phase angle of an a.c. circuit is defined as the 'angle by which the

A) supply voltage leads or lags the load current'
B) load current leads or lags the supply voltage'
C) phasor

Question 16

A 'leading' phase angle indicates a __________ load

A) purely resistive
B) resistive-inductive
C) resistive-capacitive

Question 17

The voltage appearing across a series R-L circuit is the __________ of the voltage-drops across the resistive and inductive components

A) algebraic
B) geometric
C) 0

Question 18

The voltage appearing across a series R-L circuit may be determined by applying __________ to the voltage-drops across the resistive and inductive components.

A) simple addition
B) basic trigonometry
C) Pythagoras's Theorem

Question 19

If the voltage drop measured across the resistive component of a series R-C circuit is 90 V and the voltage drop measured across the capacitive component is 120 V, the supply voltage must be

A) 30 V.
B) 150 V.
C) 210 V
D) 0

Question 20

To convert a voltage phasor diagram into an impedance diagram, we must __________ voltage phasors __________ the reference phasor.

A) multiply, by
B) divide, by
C) add the, to
D) subtract the, to

Question 21

The impedance of an a.c. series R-L-C circuit is the __________ of the __________, __________, and the __________

A) vector-sum, resistance, inductive reactance, capacitive reactance
B) algebraic-sum, resistance, inductive reactance, capacitive reactance
C) vector-sum, resistance, inductance, capacitance.
D) algebraic-sum, resistance, inductance, capacitance

Question 22

A series a.c. circuit has an inductive reactance of 60 ohms and a capacitive reactance of 20 ohms. The equivalent circuit has a reactance of __________ ohms, and a __________ phase angle

A) 80 ohms, leading
B) 80 ohms, lagging
C) 40 ohms, leading
D) 40 ohms, lagging

Question 23

Series resonance can only occur in a __________ a.c. circuit.

A) purely resistive
B) resistive-inductive
C) resistive-capacitive
D) resistive-inductive-capacitive

Question 24

Series resonance will occur whenever a circuit's

A) resistance equals its reactance
B) reactance equals its impedance
C) inductive reatance equals its capacitive reactance

Question 25

When series resonance occurs, the circuit's

A) resistance will equal its impedance
B) phase angle is zero
C) resistive voltage drop equals the supply voltage
D) each of the above

Question 26

At series resonance, if the circuit's resistance is significantly lower than its reactance, then the voltage drops appearing across the reactive components

A) will equal the supply voltage
B) may be significantly less than the supply voltage
C) may be significantly higher than the supply voltage