AC Fundamentals, Circuits & Circuit Theory Mcqs - Set 2

1)   Two waves of the same frequency have opposite phase when the phase angle between them is_________?

a. 360°
b. 180°
c. 90°
d.
Answer  Explanation 

ANSWER: 180°

Explanation:
No explanation is available for this question!


2)   The power consumed in a circuit element will be least when the phase difference between the current and voltage is________?

a. 180″
b. 90°
c. 60°
d.
Answer  Explanation 

ANSWER: 90°

Explanation:
No explanation is available for this question!


3)   For the same peak value, which of the following wave has the least mean value ?

a. half wave rectified sine wave
b. triangular wave
c. sine wave
d. square wave
Answer  Explanation 

ANSWER: half wave rectified sine wave

Explanation:
No explanation is available for this question!


4)   The r.m.s. value and mean value is the same in the case of___________?

a. triangular wave
b. sine wave
c. square wave
d. half wave rectified sine wave
Answer  Explanation 

ANSWER: square wave

Explanation:
No explanation is available for this question!


5)   Form factor for a sine wave is________?

a. 1.414
b. 0.707
c. 1.11
d. 0.637
Answer  Explanation 

ANSWER: 1.11

Explanation:
No explanation is available for this question!


6)   For a sine wave with peak value Imax the r.m.s. value is_______?

a. 0.5 Imax
b. 0.707
c. 0.9
d. 1.414 Lmax
Answer  Explanation 

ANSWER: 0.707

Explanation:
No explanation is available for this question!


7)   For a sine wave with peak value Emax _______ 8.30. the average value is?

a. 0.636 Emax
b. 0.707 Emax
c. 0.434 EWc
d. lAUEmax
Answer  Explanation 

ANSWER: 0.636 Emax

Explanation:
No explanation is available for this question!


8)   Form Factor is the ratio of__________?

a. average value/r.m.s. value
b. average value/peak value
c. r.m.s. value/average value
d. r.m.s. value/peak value
Answer  Explanation 

ANSWER: r.m.s. value/average value

Explanation:
No explanation is available for this question!


9)   The r.m.s. value of a sinusoidal A.C. current is equal to its value at an angle of_______degrees?

a. 90
b. 60
c. 45
d. 30
Answer  Explanation 

ANSWER: 45

Explanation:
No explanation is available for this question!


10)   Capacitors for power factor correction are rated in_________?

a. kW
b. kVA
c. kV
d. kVAR
Answer  Explanation 

ANSWER: kVAR

Explanation:
No explanation is available for this question!


11)   For a frequency of 200 Hz, the time period will be__________?

a. 0.05 s
b. 0.005 s
c. 0.0005 s
d. 0.5 s
Answer  Explanation 

ANSWER: 0.005 s

Explanation:
No explanation is available for this question!


12)   Capacitive reactance is more when_______?

a. capacitance is less and frequency of supply is less
b. capacitance is less and frequency of supply is more
c. capacitance is more and frequency of supply is less
d. capacitance is more and frequency of supply is more
Answer  Explanation 

ANSWER: capacitance is less and frequency of supply is less

Explanation:
No explanation is available for this question!


13)   Time constant of an inductive circuit___________?

a. increases with increase of inductance and decrease of resistance
b. increases with the increase of inductance and the increase of resistance
c. increases with decrease of inductance and decrease of resistance
d. increases with decrease of inductance and increase of resistance
Answer  Explanation 

ANSWER: increases with increase of inductance and decrease of resistance

Explanation:
No explanation is available for this question!


14)   Poor power factor________?

a. reduces load handling capability of electrical system
b. results in more power losses in the electrical system
c. overloads alternators, transformers and distribution lines
d. results in more voltage drop in the line
e. results in all above
Answer  Explanation 

ANSWER: results in all above

Explanation:
No explanation is available for this question!


15)   In series resonant circuit, increasing inductance to its twice value and reducing capacitance to its half value__________?

a. will change the maximum value of current at resonance
b. will change the resonance frequency
c. will change the impedance at resonance frequency
d. will increase the selectivity of the circuit
Answer  Explanation 

ANSWER: will increase the selectivity of the circuit

Explanation:
No explanation is available for this question!


16)   Inductance affects the direct current flow__________?

a. only at the time of turning off
b. only at the time of turning on
c. at the time of turning on and off
d. at all the time of operation
Answer  Explanation 

ANSWER: at the time of turning on and off

Explanation:
No explanation is available for this question!


17)   In a highly capacitive circuit the__________?

a. apparent power is equal to the actual power
b. reactive power is more than the apparent power
c. reactive power is more than the actual power
d. actual power is more than its reactive power
Answer  Explanation 

ANSWER: reactive power is more than the actual power

Explanation:
No explanation is available for this question!


18)   Inductance of a coil Varies__________?

a. directly as the cross-sectional area of magnetic core
b. directly as square of number of turns
c. directly as the permeability of the core
d. inversely as the length of the iron path
e. as A. to (d)
Answer  Explanation 

ANSWER: as A. to (d)

Explanation:
No explanation is available for this question!


19)   Pure inductive circuit____________?

a. consumes some power on average
b. does not take power at all from a line
c. takes power from the line during some part of the cycle and then returns back to it during other part of the cycle
d. none of the above
Answer  Explanation 

ANSWER: takes power from the line during some part of the cycle and then returns back to it during other part of the cycle

Explanation:
No explanation is available for this question!


20)   Power factor of the following circuit will be zero__________?

a. resistance
b. inductance
c. capacitance
d. both B. and C.
Answer  Explanation 

ANSWER: both B. and C.

Explanation:
No explanation is available for this question!