1) The Q meter works on the principle of
a. Series resonance
b. Parallel resonance
c. Both (a) and (b)
d. Neither series resonance nor parallel resonance
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2) If C4 is the capacitance and R4 is the resistance of Hay’s bridge, then the Q factor of Hay’s bridge is given by
a. 1 / ωC4R4
b. ωC4R4
c. ωC4 / R4
d. ωR4 / C4
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3) The Hay’s bridge is suitable for the measurement of inductances of coils with Q factor
a. More than 10
b. Less than 1
c. More than 1
d. Less than 10
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4) Anderson bridge is suitable for the measurement of
a. Resistance
b. Inductance
c. Capacitance
d. All of these
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5) The dielectric loss of pure capacitor is equal to
a. 1
b. 0
c. Maximum
d. None of these
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6) If δ is the loss angle then the dissipation factor is given by
a. sin δ
b. cos δ
c. tan δ
d. cot δ
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7) The Schering bridges can be used at
a. low voltage
b. high voltage
c. medium voltage
d. both (a) and (b)
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8) The bridge suitable for the measurement of capacitance is /are
a. Anderson’s bridge
b. Hay’s bridge
c. Owen’s bridge
d. None of these
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9) Schering bridges are used for the measurement of
a. Unknown capacitance
b. Dielectric loss
c. Power factor
d. All of these
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10) The Ac Bridge which is used for the measurement of frequency is
a. Schering bridge
b. Wien bridge
c. Hay’s bridge
d. Anderson bridge
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11) The Wien’s bridge is suitable for the measurement of frequency of the range of
a. Less than 100 Hz
b. 100 Hz to 100 kHz
c. 1 kHz to 100 MHz
d. More than 100 MHz
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12) For the measurement of unknown inductance in terms of known capacitance, the suitable ac bridges are
a. Maxwell and Schering bridge
b. Maxwell and Wien’s bridge
c. Maxwell and hay’s bridge
d. Hay’s and Wien’s bridge
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13) If a capacitor is connected across a portion of resistance of multiplier of the wattmeter then the pressure coil of the circuit becomes
a. Inductive
b. Non inductive
c. Capacitive
d. Non capacitive
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14) Shielding of the capacitor is done to
a. Make the value of capacitor definite
b. Balance the bridge without any problem
c. Both (a) and (b)
d. None of these
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15) In ac bridges, the Wagner earth devices are used to
a. Remove all the earth capacitances from the bridge circuit
b. Remove harmonics
c. Reduce error caused by stray electric field
d. All of these
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16) At 2 MHz, the resonance is obtained with a resonating capacitance value of 12 pF and at 400 kHz, the resonance is obtained with resonating capacitance value of 320 pF. Then the self capacitance of the coil is
a. 0.62 pF
b. 0.83 pF
c. 1.2 pF
d. 1.5 pF
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17) The given figure shows an ac bridge which is balanced at 100 Hz.
Fig : AC Bridge
The quality factor of the coil will be
a. 149
b. 159
c. 169
d. 189
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18) In case of dc supply and in case of ac supply, the torque produced is
a. Directly proportional to power, inversely power to power
b. Directly proportional to power, directly proportional to power
c. Inversely proportional to power, inversely proportional to power
d. Inversely proportional to power, directly proportional to power
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Answer
Explanation
Related Ques
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ANSWER: Directly proportional to power, directly proportional to power
Explanation:
No explanation is available for this question!
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19) The scale of dynamometer wattmeter is
a. Approximately uniform
b. Cramped at the middle
c. Cramped at the end points
d. Crowded in the first half
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20) In standard wattmeters, the error caused by the voltage coil is overcome by
a. Connecting a high inductive resistance in series to the voltage coil
b. Connecting a high inductive resistance in parallel to the voltage coil
c. Connecting a compensating winding in series to the voltage coil
d. Connecting a compensating winding in parallel to the voltage coil
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Answer
Explanation
Related Ques
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ANSWER: Connecting a compensating winding in series to the voltage coil
Explanation:
No explanation is available for this question!
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21) In a dynamometer type wattmeter, the pressure coil connected across the load terminal is
a. Highly inductive
b. Highly capacitive
c. Highly resistive
d. Non inductive
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22) The dynamometer wattmeter’s are
a. More accurate on dc supply
b. More accurate on ac supply
c. Equally accurate on both ac and dc supply
d. None of these
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23) Due to the inductance in the pressure coil of dynamometer type wattmeter, the reading will be
a. High for both leading and lagging power factors
b. Low for both leading and lagging power factors
c. High for lagging power factor and low for leading power factor
d. Low for lagging power factor and high for leading power factor
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Answer
Explanation
Related Ques
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ANSWER: High for lagging power factor and low for leading power factor
Explanation:
No explanation is available for this question!
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24) What will happen if the current coil and potential coil of dynamometer type wattmeter is interchanged?
a. Potential coil will get damaged
b. Current coil will get damaged
c. Both current coil and potential coil will get damaged
d. Neither potential coil nor current coil will get damaged
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25) In some wattmeters, a small capacitor is connected in parallel with the series resistor for
a. Reducing error due to inductance of the series resistor
b. Obtaining non inductive voltage coil current
c. Making resultant reactance capacitive
d. All of these
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26) In wattmeter’s, errors due to stray fields can be removed by
a. Proper instrument construction
b. Using brake magnet
c. Using shading ring
d. Using two separate ac magnets
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27) A dynamometer type wattmeter reads 200W when its voltage coil is connected across the load whose voltage is 150 V. if the voltage coil has internal resistance of 1800 ohm, then the power taken by the load will be
a. 163.8 W
b. 171.7 W
c. 178.9 W
d. 187.5 W
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28) In a dynamometer type meter, the error due to connections would be minimum if
a. Capacitive reactance of pressure coil is greater than its inductive reactance
b. Capacitive reactance of pressure coil is equal to its inductive reactance
c. Capacitive reactance of pressure coil is lesser than its inductive reactance
d. Capacitive reactance of current coil is equal to its inductive reactance
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Answer
Explanation
Related Ques
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ANSWER: Capacitive reactance of pressure coil is equal to its inductive reactance
Explanation:
No explanation is available for this question!
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29) To avoid wastage of power during calibration in dynamometer type wattmeter
a. Phantom loading is used
b. Brake magnet is used
c. Spring is used
d. Capacitance is used
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30) Induction wattmeter’s can be used with
a. Only AC supply
b. Only DC supply
c. Both AC and DC supply
d. None of these
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31) The frequency and supply voltage of induction wattmeter’s are
a. Constant, constant
b. Constant, variable
c. Variable, constant
d. Variable, variable
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32) In induction type wattmeter both current and pressure coils are required. For obtaining the required phase difference
a. Shaded pole principle is used
b. Two separate ac magnets are used
c. Only one ac magnets are used
d. All of these
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33) The scale of induction wattmeter extends over
a. 70 degree
b. 120 degree
c. 180 degree
d. 300 degree
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34) A wattmeter has a pressure coil resistance of 5K ohm and current coil resistance of 0.02 ohm. What load will give equal error with the two connections if the load current is 15 A at a voltage of 240 V and 0.8 power factor
a. 20 A
b. 24 A
c. 28 A
d. 32 A
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35) The readings of the two wattmeter used for the measurement of power input to a 3 phase induction motor are 850 W and 250 W respectively. The power factor of the motor is
a. 0.73
b. 0.76
c. 0.79
d. 0.85
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36) What will be the power factor of an inductive load if the reading of the two wattmeters connected to measure input power of a 3 phase induction motor is 6: 3?
a. 0.86
b. 0.89
c. 0.91
d. 0.95
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37) If the reading of the one wattmeter is four times the other wattmeter while measuring the input power of 3 phase induction motor then the power factor of the load will be
a. 0.56
b. 0.69
c. 0.74
d. 0.81
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38) In L-C connected wattmeter, compensated coil is used. The error in the wattmeter is due to power consumed by the
a. Current coil
b. Potential coil
c. Inductor
d. Capacitor
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39) The full scale current of a galvanometer with internal resistance of 800 ohm is 8 A. what will be the multiplying power of 80 ohm shunt with this galvanometer?
a. 8
b. 9
c. 10
d. 11
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40) If the reading of the two wattmeter’s is equal and opposite while measuring power in a 3 phase induction motor then the power factor of the load will be
a. Unity
b. Zero
c. 0.5 lagging
d. 0.5 leading
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