Q.121 All a.c circuits are made up of combination of _____.
A. Resistance R
B. Capacitance C
C. Inductance L
D. All of the above
Ans.: D
Q.122 What is the phase difference if a.c circuit consist only resistance?
A. 45º
B. Zero
C. 90º
D. 270º
Ans.: B
Q.123 which of the following represent Ohm’s law for a purely resistive circuit?
A. V = IR
B. I = VR
C. R = VI
D. V = I/R
Ans.: A
Q.124 In a.c circuit with resistance only the voltage and current are__
A. out of phase
B. leading
C. lagging
D. in phase
Ans.: D
Q.125 In a.c circuit the voltage is counter balanced by the _____across the resistance.
A. voltage rise
B. voltage drop
C. emf induce
D. all of the above
Ans.: B
Q.126 The resistance offered by a conductor to alternating current is ____ direct current.
A. less than
B. equal to
C. greater than
D. infinite
Ans.: C
Q.127 What is effective resistance?
A. is to distinguish ac from dc
B. is to distinguish dc from ac
C. is to distinguish ac voltage drop from dc voltage drop
D. all of the above
Ans.: A
Q.128 Which of the following relation is correct for voltage and current pure resistance is connected in a.c circuit?
A. v = Vm sin (ωt – ф) and i= Im sin ωt
B. v = Vm sin ωt and i= Im sin (ωt – ф)
C. v = Vm sin ωt and i= Im sin ωt
D. v = Vm sin ωt and i= Im sin (ωt + ф)
Ans.: C
Q.129 The circuit elements R, L, C are called ___.
A. a.c circuit
B. circuit parameters
C. d.c circuit
D. type of load
Ans.: B
Q.130 In a.c circuits the instantaneous power is calculated by taking the product of ____
A. average value of voltage and current
B. rms value of voltage and current
C. instantaneous value of voltage and current
D. peak value of voltage and current
Ans.: C
Q.131the average power in a purely resistive ac circuit is equal to the product of ___.
A. maximum value of voltage and current
B. average value of voltage and current
C. crest value of voltage and current
D. effective value of voltage and current
Ans.: D
Q.132 The resistance offered by a conductor to a.c is greater than dc due to
A. Feranti effect
B. skin effect
C. corona effect
D. proximity effect
Ans.: B
Q.133 The power factor of purely a.c circuit is __
A. leading
B. lagging
C. unity
D. any of the above
Ans.: C
Q.134 Calculate average power of a 100 ohm resistance is carrying a sinusoidal current given by 3 cos ωt.
A. 250 W
B. 350 W
C. 440 W
D. 450 W
Ans.: D
Q.135 The effective resistance is given by__.
A. Re = Power consumed/ I2
B. Re = power loss / I2
C. Re= I2/power loss
D. Re= I2/ power loss
Ans.: B