Sunday, October 28, 2012

Basic Electrical Engineering: Part-6 Objective Questions

Objective Questions From Basic Electrical Engineering:

[1] In ac circuit, the ratio of kW/kVA is
A. Power factor
B. Form factor
C. Load factor
D. Diversity factor

[2] Suppose that two ac waves have the same frequency but differ in phase by exactly 1/20 of a cycle. What is the phase difference between these two waves?
A.  18°
B.  20°
C.  36°
D.  5.73°

[3] The unit of inductance is
A. Mho
B. Hendry
C. Ohm
D. Farad

[4] What is the angular frequency of the ac signal having a frequency of 1770Hz
A.  1770 rad/s
B.  11,120 rad/s
C.  282 rad/s
D.  Data insufficient

[5] Thevenin's equivalent circuit consists of
A. Series combination of Rth, Eth, Rl
B. Series combination of Rth, Eth
C. Parallel combination of Rth, Eth, Rl
D. Parallel combination of Rth, Eth

[6] The frequency of DC supply is
A. 16 2/3 Hz
B. 60 Hz
C. 50 Hz
D. 0 Hz

[7] Load factor is defined as the ratio of
A. Max demand/ Average demand
B. Average demand/ Connected load
C. Average demand/ Max. demand
D. Connected load/ Max demand

[8] Q factor of an inductive coil is given by
A.  2π fL/R
B.  2π fr/R
C.  R/Z
D. lr/l

[9] The rms value of sinusoidal 100V peak to peak is
A. 100 V
B. 50/√2 V
C. 50 V
D. 100/√2 V

[10] Which of the following bulbs will have the least resistance?
A. 220V, 60W
B. 220V, 100W
C. 115V, 60W
D. 115V, 100W


Solution Hint:
[2] One cycle = 360°.
1/20 of cycle is 360/20 = 18°

 [4] Angular frequency ω = 2πf (rad/s)

 [7] Some of the important terms in power system:
Demand factor = maximum demand / Connected load
Diversity factor = Sum of individual max. demands / Max. demand on power station
The ratio of average load to the maximum demand during a given period is known as load factor.
Load Factor = Average Load / maximum demand

[8] Quality factor is the ratio of reactive power to average power (Q/P)
Qs = [I2XL]/[I2R]
Qs = XL/R
Qs = ωL/R 
Qs =2π fL/R

[9] Vrms = Vm/√2

 Thanks for reading....
6:00 PM
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6 comments:

  1. bimalSeptember 13, 2013 at 7:49 PM

    good question thanks *

    ReplyDelete
  2. arpan.jain.2November 18, 2013 at 2:26 AM

    can any one xpln Q.2 solution???

    ReplyDelete
  3. AnonymousAugust 26, 2014 at 8:51 PM

    I think the answer of qn no 7 is not right. The corre ct answer is c

    ReplyDelete
  4. AnonymousAugust 26, 2014 at 8:52 PM

    The answer of qn no 8 is also not right i think

    ReplyDelete
  5. adminSeptember 26, 2014 at 9:44 AM

    hi, we regret that for some of the typo errors and they are rectified....solution hint added now for this post and others too..

    ReplyDelete
  6. AnonymousJanuary 11, 2017 at 11:21 PM

    Q9 is wrong they given peak to peak voltage as 100. so peak voltage is 100/2=50 then rms=50/sqrt2

    ReplyDelete

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