Quiz: Electrical Engineering 14 Oct 2020

Quiz: Electrical Engineering
Topic: Miscellaneous

Each question carries 1 mark.
Negative marking: 1/3 mark
Time: 10 Minute

Q1. The energy stored in the magnetic field of a solenoid carrying a current of 5A is 0.5 J. What will be the stored energy if the number of turns is doubled and the current is halved?
(a) 0.25 J
(b) 0.5 J
(c) 1 J
(d) 2J

Q2. The reciprocal of susceptance is known as
(a) Reactance
(b) Admittance
(c) Susceptance
(d) Conductance

Q3. In a series circuit with R=10 Ω, Xc=12 Ω and XL=15 Ω, the current
(a) Leads the applied voltage
(b) Is in phase with the applied voltage
(c) Lags the applied voltage
(d) None of the above

Q4. The ratio of RMS and the average value of a particular waveform is called……
(a) Peak factor
(b) Crest factor
(c) Mean value
(d) Form factor

Q5. Loss of charge method can be used to measure which of the following?
(a) Insulation resistance of cable
(b) Resistance of shunt winding
(c) Resistance of transformer winding
(d) None of the above

Q6. Wien’s bridge is used to measure……….
(a) Energy
(b) Power
(c) Frequency
(d) Phase angle

Q7. In which of the type of transformer primary and secondary winding placed on the same central limb?
(a) Core type transformer
(b) Shell type transformer
(c) Cylindrical type transformer
(d) None of the above

Q8. In synchronous motor damper winding is placed at
(a) Yoke
(b) Stator
(c) Rotor
(d) Both stator and rotor

Q9. Load factor of a power station is generally
(a) Less than unity
(b) Equal to unity
(c) More than unity
(d) Equal to zero

Q10. What is the maximum load that is permitted in a power circuit?
(a) 2000 watts
(b) 3000 watts
(c) 5000 watts
(d) 10000 watts

S1. Ans.(b)
Sol. As we know, energy stored in the inductor is E=1/2 L1 I1^2=0.5 J
For solenoid, L ⍺ N^2⇒L2=4L1 (Number of turns doubled)
And I2=I1/2
∴E^’=1/2 (4L1 ) (I1/2)^2=1/2 L1 I1^2=0.5 J

S2. Ans.(a)
Sol. susceptance ⍺ 1/ reactance
Admittance ⍺ 1/ impedance
Conductance ⍺ 1/ resistance

S3. Ans.(c)
Sol. Here, XL>XC, so the circuit is inductive in nature and the current lags the applied voltage.

S4. Ans.(d)
Sol. form factor= RMS/ avg. value
Crest or peak factor= max. value/ rms value

S5. Ans.(a)
Sol. Loss of charge method is used to measure high values of resistance (insulation resistance).
methods for measurement of high resistance:
Loss of charge method
Direct deflection method
Megaohm bridge

S6. Ans.(c)
Sol. Wien’s bridge is used to measure frequency.

S7. Ans.(b)
Sol. In shell type of transformer primary and secondary winding placed on the same central limb.

S8. Ans.(c)
Sol. synchronous motors are not self-starting machines. These are made self-starting by providing damper winding in the rotor poles.

S9. Ans.(a)
Sol. load factor=(average load)/(maximum demand )
Load factor is always less than 1.

S10. Ans.(b)
Sol. maximum load for lighting points circuit= 800 watts
Maximum load for power circuit= 3000 watts


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