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DFCCIL’21 EE: Daily Practices Quiz 01-Sep-2021
Each question carries 1 mark.
Negative marking: 1/4 mark
Total Questions: 06
Q1. For a series resonant circuit at low frequency circuit impedance is ………….and at high frequency circuit impedance is…………
(a) Resistive, inductive
(b) Capacitive, resistive
(c) Capacitive, inductive
(d) Inductive, capacitive
Q2. Q-factor of a coil is 120 at resonant frequency of 2 MHz. The bandwidth will be:
(a) 16.66 KHz
(b) 56.66 KHz
(c) 10 KHz
(d) 100 KHz
Q3. Frequency can be measured by using
(a) Maxwell bridge
(b) Schering bridge
(c) Hay’s bridge
(d) Wein’s bridge
Q4. A 4 1⁄2 digit digital voltmeter can read maximum value up to.
(a) 99999
(b) 19999
(c) 99990
(d) 09999
Q5. Which one of the following methods gives voltage regulation higher than the actual value in an alternator?
(a) ZPF method
(b) MMF method
(c) emf method
(d) ASA method
Q6. Three inductors each of 60 mH are connected in delta. The value of inductance of each arm of the equivalent star connection is
(a) 10 mH
(b) 15 mH
(c) 20 mH
(d) 30 mH
SOLUTIONS
S1. Ans.(c)
Sol. For series RLC resonant circuit, below resonant frequency nature of circuit will be capacitive and above resonant frequency it is inductive in nature and vice-versa for parallel RLC resonant circuit.
S2. Ans.(a)
Sol. ACQ: Q=120, f_r=2 MHz=2000×10^3 Hz
Q=f_r/BW
∴BW=f_r/Q=(2000×10^3)/120=16.66 KHz.
S3. Ans.(d)
Sol. The Wien’s bridge use in AC circuits for determining the value of unknown frequency. The bridge measures the frequencies from 100Hz to 100kHz.
S4. Ans.(b)
Sol. A 4.5-digit display is actually five segments, one half digit and 4 full digits. Displaying maximum capability, it would read 19999.
S5. Ans.(c)
Sol. EMF method of voltage Regulation is known as “Pessimistic Method” because gives VR higher than actual.
S6. Ans.(c)
Sol. For equivalent star connection
ZY = (1/3) ZΔ
= 60/3
= 20 mH