WorksheetsConnect with Comali Round 1
Total questions: 38
Worksheet time: 13mins
1.If the DC excitation is suddenly dropped to 0, the three phase alternator _________
runs as a motor
stops to zero speed in few seconds
continues to run as motor but at lower speed.
no change in the operating
2.A two-pole alternator is running at 1500 r.p.m. Its angular velocity is ________
118 rad/s
192 rad/s
157 rad/s
212 rad/s
3. Among the following which material is used in PMDC Motors to make permanent magnet?
(I) Alnicos1
(II) Ferrites
(III) Rare Earth Material (samarium Cobalt & NIB)
only (I)
(II) & (III)
(I) & (III)
All
4.Which of the following motors is preferred for tape recorder?
Hysteresis motor
shaded pole motor
repulsion motor
universal motor
5. Two lamps 100 W and 40 W are connected in series across 230 V (alternating). Which of the
following statement is correct ?
100 W lamp will brighter
40 W lamp will glow brighter
both lamp will glow equally bright
40 W lamp will fuse
6.Three identical resistors are first connected in parallel and then in series.
The resultant resistance of the first combination to the second will be.....
9 times
1/9 times
1/3 times
3 times
7. Voltage applied across a ceramic dielectric produces an electrolytic field 100 times greater
than air. What will be the value of dielectric constant ?
50
100
150
200
8. "The total electric flux through any closed surface surrounding charges is equal to the
amount oflcharge enclosed".The above statement is associated with
Coulomb's square law
Gauss's law
Maxwell's first law
Maxwell's second law
9.A mica capacitor and a ceramic capacitor both have the same physical dimensions. Which
will have more value of capacitance ?
Ceramic capacitor
Mica capacitor
Both will have identical value of capacitance
It depends on applied voltage
10."The surface integral of the normal component of the electric displacement D over any
closed surface equals the charge enclosed by the surface".
The above statement is associated with
Gauss's law
Kirchhoff s law
Faraday's law
Lenz's law
11."The mass of an ion liberated at an electrode is directly proportional to the quantity of
electricity".The above statement is associated with
Newton's law
Faraday's law of electromagnetic
Faraday's law of electrolysis
Gauss's law
12. conductors for high voltage transmission lines are suspended from towers
to increase clearance from ground
to take care of length extension in summer
to reduce cleaence from ground
to reduce wind and snow loads
13.long transmission lines the incident component of voltage increases in magnitude and phase
as we move ________ receiving end
towards
away from
besides
below
14.In a power system there will always exist an unbalance between the demand and supply conditions of active
and reactive power and this leads to variation of __________ and __________ from their respective rated values.
frequency,voltage
voltage,power
voltage,frequency
power,voltage
15.Disruptive discharge voltage is the voltage which produces the loss of __________ strength of an insulation.
dielectric
tensile
lumped
electric
16.Dielectric strength of mica can be expected more than
500kv/mm
2500kv/mm
3500kv/mm
1250kv/mm
17.Which of the following is not the transmission voltage in America
66kv
264kv
132kv
400kv
18.In overhead transmission lines the effect of capacitance can be neglected when the length of line is less than
80km
200km
100km
160km
19.EMF Method is used for calculation of
Voltage Regulation
Efficiency
Losses
None of these
20.Slip of Induction Motor at Starting
0
1
0.1
0.3
21.Squirrel Cage Induction Motor is having
High Starting Torque
Low Starting Torque
Both A&B
None of these
22.Slip of Induction motor
Ns-Nr/Ns
Ns-Ns/Ns
Ns-Nr/Nr
None of these
23.Three Phase Slip ring Induction motor rotor is having
Three phase winding
Single Phase winding
Two Phase winding
None of these
24.Three Phase Squirrel cage Induction motor rotor is having
Three phase winding
Single Phase winding
Two Phase winding
Short Circuited Copper Bars
25. Core Losses are
A) Hysteresis loss
B) Eddy Current Loss
C) Both A&B
D) None of these
26. Copper Losses are
A) (I^2)R Losess
B) Constant Losess
C) Both A&B
D) None of these
27. Mechanical Losses are
A) core losses
B) Friction & Windage losses
C) Both A&B
D) None of these
28.What is the value of Nr when S=0.6, Ns=1000RPM
400 RPM
500 RPM
600 RPM
700 RPM
29. Slip When Nr=Ns
1
0
0.5
0.4
30.The diode in a half wave rectifier has a forward resistance RF. The voltage is Vmsinωt and the load resistance is RL. The DC current is given by _________
Vm/√2RL
Vm/(RF+RL)π
2Vm/√π
Vm/RL
31.The below figure arrives to a conclusion that _________
for Vi > 0, V0=-(R2/R1)Vi
for Vi > 0, V0=0
Vi < 0, V0=-(R2/R1)Vi
Vi < 0, V0=0
32.If the voltage of the potential barrier is V0. A voltage V is applied to the input, at what moment will the barrier disappear?
V< V0
V= V0
V> V0
V<< V0
33.A shunt regulator utilizing a zener diode with an incremental resistance of 5 Ω is fed through an 82-Ω resistor. If the raw supply changes by 1.0 V, what is the corresponding change in the regulated output voltage?
72.7 mV
73.7 mV
74.7 mV
75.7 mV
34.Determine the expression for the transfer function for the circuit shown below.
(Rf/R)/(1+jωCRfC)
(Rf/R)/(1-jωCRfC)
– (Rf/R)/(1+jωCRfC)
– (Rf/R)/(1-jωCRfC)
35.Find V4 and V5
4V and -5V respectively
-4V and 5V respectively
4V and 5V respectively
-4V and -5V respectively
36.The waveform of the current drawn by a semi-converter from a sinusoidal AC voltage source is shown in the figure. If I0=20AI0=20A, the rms value of fundamental component of the current is ___________A (up to 2 decimal places).
17.50 to 18.90
16.90 to 17.70
16.90 to 17.10
17.60 to 19.00
37.For the power semiconductor device IGBT, MOSFET, Diode and Thyristor, which one of the following statements is TRUE?
All the four are majority carrier devices.
All the four are minority carrier devices.
IGBT and MOSEFT are majority carrier devices, whereas Diode and Thyristor are minority carrier devices
MOSEFT is majority carrier devices, whereas IGBT, Diode, Thyristor are minority carrier devices.
38. In the circuit shown, the diodes are ideal, the inductance is small, and I0 ≠ 0. Which one of the following statements is true?
D1 conducts for greater than 180° and D2 conducts for greater than 180°.
D2 conducts for more than 180° and D1 conducts for 180°.
D1 conducts for 180° and D2 conducts for 180°.
D1 conducts for more than 180° and D2 conductsfor 180°.
