NHPC-JE’21 EE: Daily Practices Quiz 26-Oct-2021

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NHPC-JE’21 EE: Daily Practices Quiz

NHPC-JE’21 EE: Daily Practices Quiz 26-Oct-2021

Each question carries 1 mark.
Negative marking: 1/4 mark
Total Questions: 06
Time: 06 min.

Q1. As compared to a split phase motor, a capacitor start motor has………
(a) Higher running torque
(b) Lower starting torque
(c) Higher starting torque
(d) None of the above

Q2. Which of the following voltmeter has least power consumption?
(a) Electrostatic
(b) Moving iron
(c) Induction type
(d) Hot wire

Q3. What will be the transformation ratio of a 550/110 V, 50 Hz single-phase step-down transformer?
(a) 5
(b) 11
(c) 1.1
(d) 0.2

Q4. Diffusion capacitance of a PN junction diode………. with forward bias.
(a) Increases
(b) Decreases
(c) Remains the same
(d) May increase or decrease

Q5. The purpose of guard ring in transmission lines is to…………
(a) Reduce the reactance of the line
(b) Increase the earth capacitance of the lowest unit
(c) Reduce the transmission line losses
(d) Reduce the earth capacitance of the lowest unit

Q6. An RLC series resonance circuit boosts:
(a) Inductance
(b) Frequency
(c) Current
(d) Resistance

SOLUTIONS

S1. Ans.(c)
Sol. Decreasing order of starting torque:
Capacitor start capacitor run > capacitor start > split phase

S2. Ans.(a)
Sol. Electrostatic type has very low power consumption while induction type has very high-power consumption.

S3. Ans.(d)
Sol. Turn ratio=N1/N2 =V1/V2
Transformation ratio=N2/N1 =V2/V1 =110/550=0.2

S4. Ans.(a)
Sol. Diffusion capacitance is directly function of applied voltage or current. when forward bias voltage is applied across PN diode, a large number of charges is accumulated near the depletion layer, as a result, large diffusion capacitance occurs,

S5. Ans.(d)
Sol. The purpose of guard ring in transmission lines is to:
Reduce the earth capacitance of the lowest unit
Equal voltage distribution across each disc

S6. Ans.(c)
Sol. RLC series resonance circuit:
XL=XC and Z=R
As impedance is lower, the current will be maximum.