# PI (AC/DC) simulation/MCQ on AC Circuits Sample Test,Sample questions

## Question: ` A series-resonant circuit implies`

1.zero pf and maximum current

2.unity pf and maximum current

3.unity pf and minimum current

4.zero pf and minimum current

Posted Date:-2022-10-09 15:21:35

## Question: ` Electrical power converted into heat due to the flow of an alternating current through an ohmic resistance is called the â€¦â€¦.. power.`

1.heating

2.true

3.reactive

4.apparent

Posted Date:-2022-10-09 12:24:42

## Question: ` If a series RLC circuit is excited by a voltage e = E sin Ï‰t where LC < 1/Ï‰2`

1.current lags behind the applied voltage

3.voltage across L and C are equal

4.current is in phase with the applied voltage

Posted Date:-2022-10-09 12:44:19

## Question: ` In a series R-L-C circuit, the magnitude of resonance frequency can be changed by changing the value of`

1.R only.

2.L only.

3.C only.

4.L or C.

Posted Date:-2022-10-09 15:19:36

## Question: ` In an ac circuit, the applied voltage and current drawn are represented as v = Vmax sin Ï‰t and i = Imax sin (Ï‰t + Ï•). The pf of the circuit is`

1.sin Ï•

2.cos Ï• (lagging)

4.none of these

Posted Date:-2022-10-09 12:37:27

## Question: ` In an R-L-C parallel circuit, the line current at resonance is`

1.minimum at unity power factor

2.minimum at lagging pf

4.maximum at lagging pf

Posted Date:-2022-10-09 15:26:12

## Question: ` In the 2 WM method of power measurement, one of the W.M. will show negative reading when the load pf angle is strictly`

1.less than 30Â°

2.less than 60Â°

3.greater than 30Â°

4.greater than 60Â°

Posted Date:-2022-10-09 15:37:16

## Question: ` In the case of a delta connected load, if one resistor is removed, the power will become`

1.zero

2.one-third

3. two-third

4.None of these

Posted Date:-2022-10-09 15:35:06

## Question: ` The power factor of an inductive circuit is usually improved by adding a capacitor to it in:`

1. series

2.parallel

3.either in series or parallel

4.None of These

Posted Date:-2022-10-09 15:11:55

## Question: ` The RMS value of a sine wave is 100 A. Its peak value is`

1.70.7 A

2.141 A

3.150 A

4.282.8 A

Posted Date:-2022-10-09 12:21:49

## Question: ` Under the condition of resonance in the RLC series circuit, the power factor of the circuit is`

1.0.5 lagging

3.unity

4.zero

Posted Date:-2022-10-09 15:09:43

## Question: `16. In a 3-phase system, the EMFs are`

1.30Â° apart

2.40Â° apart

3.90Â° apart

4.120Â° apart

Posted Date:-2022-10-09 15:30:55

## Question: `A 100 W, 100 V bulb is to be supplied from 220 V, 50 Hz supply. Which of the following arrangements is preferable?`

1.Additional pure inductance in series with lamp.

2.Additional resistance in series with the lamp.

3.Additional inductance and capacitance in series with the lamp.

4.None of the above

Posted Date:-2022-10-09 12:40:58

## Question: `A 3-phase 6.6/0.4 kV transformer is to supply a load at 230 V. Its secondary should be connected in`

1.star

2.delta

3.open-delta

4.series

Posted Date:-2022-10-09 15:34:07

## Question: `A constant current of 2.8 A exists in a resistor. The RMS value of current is`

1.2.8 A

3.1.4 A

4.Undefined

Posted Date:-2022-10-09 12:19:52

## Question: ```A current is said to be alternating when it changes in ```

1.magnitude only

2.direction only

3.both magnitude and direction

4.none of the above

Posted Date:-2022-10-09 12:12:52

## Question: `A current is said to be direct current when its`

1.magnitude remains constant with time

2.magnitude changes with time

3.direction changes with time

4.magnitude and direction changes with time

Posted Date:-2022-10-09 11:48:07

## Question: `A lamp load is given a supply from 3-phase, 4-wire 230/400 V, A.C. supply system. If a 3- phase motor is now switched on across the same supply, then neutral current will`

1.increase

2.decrease

3.remain unchanged

4.be unpredictable

Posted Date:-2022-10-09 15:39:55

## Question: `A parallel resonant circuit can be employed`

1.as a high impedance

2.to amplify certain frequencies

3.to amplify voltage

4. both high impedance and reject a small band of frequencies

Posted Date:-2022-10-09 15:29:04

## Question: `A small capacitance is added to a highly inductive circuit,`

1.the angle between voltage and current will increase

2.the pf will increase

3.the pf will decrease

4.the power drawn will decrease

Posted Date:-2022-10-09 15:08:39

## Question: `A two-terminal black box contains a series combination of a resistor and an unknown two-terminal linear device. As soon as the battery is connected to the black box the current is found to be zero. The device is`

1.an inductor

2.a capacitor

3.a resistor

4.an unknown

Posted Date:-2022-10-09 12:29:31

## Question: `Average power in a purely resistive circuit is equal to`

1.zero

2.product of average values of current and voltage

3.product of peak values of current and voltage

4.product of rms or effective values of current and voltage

Posted Date:-2022-10-09 12:25:43

## Question: ```Consider the following statements with respect to a series R-L-C circuit under resonance condition: All the applied voltage appears across R. There is no voltage across either L or C. The voltage across L and C equal and equal to their maximum values. Of these statements```

1.1 alone is correct.

2.2 alone is correct.

3.1 and 3 are correct.

4.1 and 2 are correct.

Posted Date:-2022-10-09 15:18:20

## Question: `If an alternating triangular voltage is applied to a resistor, the shape of the current waveform will be â€¦â€¦. waveform.`

1.triangular

2.sawtooth

3.sinusoidal

4.square

Posted Date:-2022-10-09 12:26:23

## Question: `In a series R-C circuit current â€¦â€¦.. with the increase in frequency.`

1.increases

2.decreases

3.remains unaltered

4.None of the above

Posted Date:-2022-10-09 12:39:29

## Question: `In a series R-L circuit`

1.voltage drops across R and L are in phase

2.voltage drop across L leads the voltage drop across R by 90Â°

3.voltage drop across L lags behind the voltage drop across R by 90Â°

4.voltage drops across R and L are in phase opposition

Posted Date:-2022-10-09 12:36:07

## Question: `In ac circuits the power curve is a sine wave having`

1.same frequency as that of voltage

2.double the frequency of the voltage

3.half the frequency of the voltage

4.none of the above

Posted Date:-2022-10-09 12:24:02

## Question: `In the balanced 3-phase voltage system generated by a star connected alternator, VYB lags ER by`

1.90 degrees

2.120 degrees

3.60 degrees

4.30 degrees

Posted Date:-2022-10-09 15:36:06

## Question: `Q-factor of a coil is the measure of its`

1.selectivity

2.retentivity

3.resistivity

4.self inductance

Posted Date:-2022-10-09 12:38:37

## Question: `The angular frequency of an alternating quantity is a mathematical quantity obtained by multiplying the frequency f of the alternating quantity by a factor`

1.Ï€/2

2.Ï€

3.2 Ï€

4.4 Ï€

Posted Date:-2022-10-09 12:19:00

## Question: `The apparent power and active power is drawn are equal for an ac circuit of:`

1.inductive type

2.capacitive type

3.resistive type

4.none of these

Posted Date:-2022-10-09 12:33:27

## Question: `The Parallel R-C circuit behaves as a purely capacitive circuit at â€¦â€¦â€¦â€¦ frequencies.`

1. very low

2. low

3.high

4.very high

Posted Date:-2022-10-09 15:14:35

## Question: `The purely inductive circuit takes power from the ac mains when`

1.both applied voltage and current increase

2.both applied voltage and current decrease

3.applied voltage decreases but current increases

4.applied voltage increases but current decreases

Posted Date:-2022-10-09 12:27:30

## Question: `The quantity (12 + j9) represents the resistive and reactive components of the current drawn by an ac circuit. The phase angle between the applied voltage and the current is:`

1.41.4Â°

2.53.13Â°

3.36.87Â°

4.48.6Â°

Posted Date:-2022-10-09 15:13:15

## Question: `The ratio of effective value to average value is called the â€¦. factor.`

1.form

2.peak

3.average

4.Q-factor

Posted Date:-2022-10-09 12:20:41

## Question: `The reactance offered by a capacitor to alternating current of frequency 50 Hz is 10 Î©. If the frequency is increased to 100 Hz, reactance becomes:`

1.20 ohms

2.5 ohms

3.2.5 ohms

4.40 ohms

Posted Date:-2022-10-09 12:30:12

## Question: `The source in the circuit shown is a sinusoidal source. The supply voltage across various elements is marked in the figure. The input voltage is`

1.10 V

2.5 V

3.27 V

4.24 V

Posted Date:-2022-10-09 12:42:13

## Question: ```The standard supply frequency in India is ```

1.25 Hz

2.50 Hz

3.60 Hz

4.100 Hz

Posted Date:-2022-10-09 12:14:31

## Question: `When a sinusoidal voltage is applied across R-L series circuit having R = XL, the phase angle will be:`

1.90Â°

2.45Â° lag

Posted Date:-2022-10-09 12:34:23

## Question: `When a sinusoidal voltage is applied across the R-L parallel circuit so that R = XL, the phase angle will be:`

1.45Â° lag

3.90Â° lag

Posted Date:-2022-10-09 15:10:56

## Question: `When the two quantities are in quadrature the phase angle between them will be`

Posted Date:-2022-10-09 12:22:58

## Question: `Which of the following statements associated with a purely capacitive circuit is not true?`

1.Power consumed is zero.

2.Heat produced is zero.

3.Power factor is unity.

4.Work done is zero.

Posted Date:-2022-10-09 12:28:33

1.pf is unity