Complex AC MCQs

Question 1

Which of the following refers to a parallel circuit?

Accepted Answer

The current through any one element is less than the source current

Answer

The current through each element is Same

Answer

The voltage across element is in proportion to its resistance value

Answer

The equivalent resistance is greater than any one of the resistors

Question 2

A phasor is

Accepted Answer

a line which represents the magnitude and phase of an alternating quantity

Answer

a line representing the magnitude and directionof an alternating quantity

Answer

a coloured tag or band for distinction between different phases of a 3-phase supply

Answer

an instrument used for measuring phases of an unblanced 3-phase load

Question 3

A parallel 4C circuit in resonance will

Accepted Answer

have a high impedance

Answer

have a high voltage developed across each inductive and capacitive section

Answer

act like a resistor of low value

Answer

have current in each section equal to the line current

Question 4

The power taken by a 3-, load is given by the expression

Accepted Answer

VOL cos

Answer

/3- VLIL sin (1)

Answer

3 VL1L sin

Answer

3 VL1L cos (1)

Question 5

The least number of 1-4) wattmeters required to measure total power consumed by an unbalanced load fed from a 3-(1), 4-wire system is

Accepted Answer

3

Answer

I

Answer

2

Answer

4

Question 6

On a three-phase supply floating neutrals undesirable because it may give rise to high voltage across the load low voltage across the load unequal line voltages across the load unequal phase voltages across the load a 3-0 balanced delta-connected load plied at 240 V A.C., the wattmeter dings are ? 1710 and 3210. What is current?

Accepted Answer

2A

Answer

1A

Answer

15.86 A

Answer

0.864A

Question 7

Two wattmeters connected to measure the power input to a balanced 3-4) circuit indicate 2500 W and 500 W respectively.What is the power factor?

Accepted Answer

0.655

Answer

0.3

Answer

0.455

Answer

0.55

Question 8

A serie s R-L-C circuit has R=80 C =300 12, L=100 p. Hand p F, V=20 V The current at resonance will be

Accepted Answer

0.25 A

Answer

0.125 A

Answer

(6)1.25 A

Answer

5 A

Question 9

For the full wave rectified sine wave the r.m.s. value is max

Accepted Answer

0.7071

Answer

0.636

Answer

0.318 1

Answer

zero