EE SHORT NOTES AC FUNDAMENTALS 2

21

A sine wave of voltage varies from zero to maximum of 200 V. How much is the voltage at the instant of 30° of the cycle ?
100V
[other wrong options are – 50V, 82.8V, 173.2 V, ]

22

The power consumed in a circuit element will be least when the phase difference between the current and voltage
90°
[other wrong options are – 180°, 60°, 0°, ]

23

The form factor is the ratio of
r.m.s. value to average value
[other wrong options are – Peak value to r.m.s. value, Average value to r.m.s. value, None of these, ]

24

Which of the following is not a non-linear element ?
Heater coil
[other wrong options are – Transistor, Diode, Electric arc with unlike electrodes, ]

25

At half power points of a resonance curve, the current is____ times the maximum current.
1/ √2
[other wrong options are – 1/2, √2, 2, ]

26

The product of apparent power and cosine of the phase angle between circuit voltage and current is
True power
[other wrong options are – Reactive power, Volt-amperes, Instantaneous power,]

27

The power is measured in terms of decibles in case of
Electronic equipment
[other wrong options are – Transformers, Current transformers, Auto-transformers, ]

28

The safest value of current the human body can carry for more than 3 second is
9 mA

[other wrong options are – 4 mA, 15 mA, 25 mA, ]

29

The power factor at resonance in RLC parallel circuit is
Unity
[other wrong options are – Zero, 0.08 Lagging, 0.8 Leading, ]

30

Capacitors for power factor correction are rated in
kVAR
[other wrong options are – kW, kVA, kV, ]

31

For 200 V r.m.s. value triangular wave, the peak voltage will be
346 V
[other wrong options are – 200 V, 222 V, 282 V, ]

32

Two waves of the same frequency have opposite phase when the phase angle between them is
180°
[other wrong options are – 360°, 90°, 0°, ]

33

A network is said to be non-linear if it does not satisfy
Both (A) and (B)
[other wrong options are – Homogeneity condition, Superposition condition, Associative condition, ]

34

The value of operator j2 is equal to
 -1
[other wrong options are – Zero,  +1, √-1, ]

35

The power factor of a D.C. circuit is always
Unity
[other wrong options are – Less than unity, Greater than Unity, Zero, ]

36

At____ frequencies the parallel R-L circuit behaves as purely resistive.
Very high
[other wrong options are – Low, Very low, High, ]

37

If resistance is 20 ω and inductance is 2H in a RL series circuit, then time constant of this circuit will be
0.1 S
[other wrong options are – 0.001 S, 10 S, 100 S, ]

38

The transient currents are associated with the
Changes in the stored energy in the inductors and capacitors
[other wrong options are – Impedance of the current, Applied voltage to the circuit, Resistance of the circuit, ]

39

The best place to install a capacitor is
Across the terminals of the inductive load
[other wrong options are – Very near to inductive load, Far away from the inductive load, Any where, ]

40

For a sine wave with peak value Emax the average value is
0.636 Emax
[other wrong options are – 0.707 Emax, 0.434 Emax, 1.414 Emax, ]