Module-11
1. Which is the best conductor of electricity
Iron
Silver
Aluminum
Carbon
Correct Answer : b Explanation : The best conductor of electricity is pure silver
2. For which of the following ‘ampere second’ could be the unit
Reluctance
Charge
Power
Energy
Correct Answer : b Explanation : The SI derived unit of electric charge is the coulomb, which is defined as
an ampere second.
3. 6 ohm resistor having 2 A current will dissipate the power of
12 watts
4 watts
24 watts
8 watts
Correct Answer : c Explanation : P = I2R= 4*6= 24W
4. Which power should be connected to Anode/Cathode to make PN Diode
forward Biased?
+7V, +10V
3V, +5V
+0.3V, +5V
+5V, 1V
Correct Answer : d Explanation : during forward bias condition,anode potential should be greater than cathode
potential
5. The resistance of a few meters of wire conductor in closed electrical circuit
is
practically zero
low
high
very high
Correct Answer : a Explanation : When wire conductor is made for smooth electric current carrying then the
resistance of the wire conductor is kept low or as near to zero.
6. Which of these formulae gives the voltage gain of an amplifier?
Vout/ Vin
Vin/ Vout
Vout/ Iin
Vin x hfe
Correct Answer : a Explanation : Gain is defined as the ratio of output to input
7. The maximum efficiency of a distribution transformer is
at no load
at 60% to 70% full load
at 80% full load
at full load
Correct Answer : b Explanation : The main difference between power and distribution transformer is
distribution transformer is designed for maximum efficiency at 60% to 70% load as normally doesn't operate at full load all
the time.
8. Transformer breaths in when
load on it increases
load on it decreases
load remains constant
none of the above
Correct Answer : b Explanation : When the oil cools down, air from the atmosphere is drawn in to
the transformer. This is called breathing in of the transformer. Use of Silica gel breather. During the breathing process, the
incoming air may consist of moisture and dirt which should be removed in order to prevent any damage
9. No-load current of a transformer has
has high magnitude and low power factor
has high magnitude and high power factor
has small magnitude and high power factor
has small magnitude and low power factor
Correct Answer : d Explanation : No-load current of a transformer has small magnitude and low power
factor
10. On which of the following factors skin effect depends
Frequency of the current
Size of the conductor
Resistivity of the conductor material
All of the above
Correct Answer : d Explanation : Factors affecting skin effect: Frequency, Diameter, The shape of the
conductor, Type of material.
11. The power transformer is a constant
voltage device
current device
power device
main flux device
Correct Answer : d Explanation : The power transformer is a constant flux device.
12. The ratio of starting torque to running torque in a synchronous motor is
zero
one
two
infinity
Correct Answer : a Explanation : The torque developed at the instant of
starting of a motor is called as starting torque. Starting torque may be greater than running torque in some cases, or it may
be lesser.
13. In a 3-phase, 4-pole, 50 Hz synchronous motor, the frequency, pole
number and load torque all are halved. The motor speed will be
3000 r.p.m.
1500 r.p.m.
750 r.p.m.
none of the above
Correct Answer : b Explanation : Ns=120f/P
14. What is the voltage gain of an amplifier at the half power points on the
amplifier response curve?
0.5
0.707
1.414
2
Correct Answer : b Explanation : These half power points corresponds to a fall in gain of 3dB (0.7071)
relative to its maximum dB value. Most amplifiers and filters have a flat frequency response characteristic in which the
bandwidth or passband section of the circuit is flat and constant over a wide range of frequencies.
15. A differential amplifier has a differential gain of 20,000. CMMR=80dB.
The common mode gain is given by
0.5
0
Correct Answer : a Explanation : CMRR = Ad/Acm
16. Specific energy consumption is least in _______ service
main line
urban
Suburban
None of these
Correct Answer : a Explanation : Since main line is allocated for transmission purpose, the Specific
energy consumption is less.
17. _______ was the first city in India to adopt electric traction.
Delhi
Madras
Calcutta
Bombay
Correct Answer : d Explanation : Bombay was the first city in India to adopt electric
traction.
18. _______ frequency is not common in low frequency traction system
40 Hz
25 Hz
16 Hz
None of the above
Correct Answer : a Explanation : Low-frequency voltage fluctuation of traction network
around 40 Hz has been found frequently, which affects both traction power supply system (TPSS) and utility system
seriously.
19. Which of the following is the output of Source Selection?
Proposals.
Evaluation criteria.
Contract negotiation.
Contract.
Correct Answer : d Explanation : People is the least constraint for a project
20. Which of the following is an acceptable reason in a project delay?
Strike of labors
Delay integrating license
Bad quality work
None of the above
Correct Answer : b Explanation : Delay integrating license is one of the main and acceptable reason
in a project delay.
21. For a base current of 10 μA, what is the value of collector current in
common emitter if βdc = 100
10 μA
100 μA
1 mA
10 mA
Correct Answer : c Explanation : IC = 10 x 100 μA = 1 mA.
22. Terminal representing control input of BJT
Emitter
Base
Collector
None of the above
Correct Answer : b Explanation : Collector current can be controlled by varying the base
current
23. Transconductance of BJT is
dIE/dIC
VBE/IE
IE/IC
Ic/VBE
Correct Answer : d Explanation : The transconductance for the bipolar transistor can be
expressed as. where IC = DC collector current at the Q-point, and VT = thermal voltage, typically about 26 mV at room
temperature.
24. Information to develop a project network is collected from the
Organization breakdown structure
Work breakdown structure
Budget
Project proposal
Correct Answer : b Explanation : In a Work Breakdown Structure such elements (activity or
deliverable), also known as work packages, are the items that are estimated in terms of resource requirements, budget and
duration; linked by dependencies; and scheduled.
25. A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of
rotor e.m.f. will be
200 Hz
50 Hz
2 Hz
0.2 Hz
Correct Answer : c Explanation : s = 0.04, rotor frequency = s*f = 0.04*50 = 2 Hz
Question 26
N-channel FETs are superior to p-channel FETs because
mobility of electrons is smaller than that of holes
mobility of electrons is greater than that of holes
they consume less power
they have high switching time
Correct Answer : b Explanation : High switching device. (mobility of electrons is high)
