Quiz: Electrical Engineering 09 Jan 2021

Quiz: Electrical Engineering
Exam: UPPCL-JE
Topic: Miscellaneous

Each question carries 1 mark.
Negative marking: 1/4 mark
Time: 10 Minute

Q1. What will be the value of susceptibility when the curie constant value is 0.2 and the difference in critical temperature and paramagnetic Curie temperature is 0.01?
(a)2
(b)200
(c)0.02
(d)20

Q2. In FET, the current flow is mainly due to
(a)Majority carriers
(b)Minority carriers
(c)Both a and b
(d)None of the above

Q3. The gate of a JFET is ………… biased
(a)Reverse
(b)Forward
(c)Reverse as well as forward
(d)None of the above

Q4. Which of the following has the least power consumption?
(a)Argon bulb
(b)LED bulbs
(c)CFL tubes
(d)Tubelight

Q5. Candela is the unit of
(a)Luminous flux
(b)Luminous intensity
(c)Wavelength
(d)Frequency

Q6. The typical value of SCR for modern alternator is
(a)1.0
(b)1.2
(c)1.5
(d)0.5

Q7. An SCR is considered to be a semi-controlled device because
(a)it can be turned OFF but not ON with a gate pulse.
(b) it conducts only during one half cycle of an alternating current wave.
(c) it can be turned ON but not OFF with a gate pulse.
(d)it can be turned ON only during one half cycle of an AC.

Q8. If the conductor radius increases, inductance of the line-
(a) increases
(b) decreases
(c) remains same
(d) may increase or decrease

Q9. Cumulatively compounded motors are used where we require ………
(a) variable speed
(b) poor speed regulation
(c) sudden heavy loads for short duration
(d) none of the above

Q10. A parallel resonance……….
(a) circuit impedance is minimum
(b) power factor is zero
(c) line current is maximum
(d) power factor is unity

SOLUTIONS
S1. Ans.(d)
Sol. The magnetic susceptibility(x_m )=C/(T-Ө)
Where, C = curie constant = 0.2
T = Critical Temperature
θ = Curie Temperature
The difference in critical temperature and paramagnetic Curie temperature is (T − θ) = 0.01
∴x_m=C/(T-Ө)=0.2/0.01=20

S2. Ans.(a)
Sol. A unipolar transistor is a field effect transistor (FET) that uses only one type of charge for conduction from drain to source i.e., either electrons (n-channel FET) or holes (P-channel FET).
In FET, the current flow is mainly due to majority carriers.

S3. Ans.(a)
Sol. The magnitude of the current flowing through the channel between the Drain and the Source terminals is controlled by a voltage applied to the Gate terminal, which is a reverse-biased. In an N-channel JFET this Gate voltage is negative while for a P-channel JFET the Gate voltage is positive.

S4. Ans.(b)
Sol. LED bulbs

S5. Ans.(b)
Sol. The candela is the SI unit of luminous intensity.

S6. Ans.(d)
Sol. 0.5

S7. Ans.(c)
Sol. By applying gate pulse the SCR can be turned ON during forward blocking mode. But SCR cannot be turned OFF by applying gate pulse. It automatically turns off when anode current is below the Holding current. That is why it is called semi controlled rectifier.

S8. Ans.(b)
Sol. Inductance of a line.
L = 2×10-7 ln[GMD/GMR] H/m/phase
and. GMR α Radius of the conductor
If radius increases then GMR will increase and inductance will decrease.

S9. Ans.(c)
Sol. Cumulatively compounded motors are used where we require sudden heavy loads
for short duration.

S10. Ans.(d)
Sol. In parallel resonance condition:
Circuit impedance is maximum. Hence, current will be minimum.
Power factor unity

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