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Browse complete papersA circuit contains only dependent sources and resistors. What is the value of the Thevenin equivalent voltage (\( V_{th} \)) looking into any pair of terminals?
Infinite
Equal to the supply voltage of the dependent source
Zero
Unity
Correct answer
Infinite
For a network consisting of linear resistors and independent sources, if the load resistance is fixed and the source resistance is variable, maximum power is transferred to the load when:
Source resistance equals load resistance
Source resistance is minimum (ideally zero)
Source resistance is maximum
Source resistance is half the load resistance
Correct answer
Source resistance equals load resistance
Which of the following methods is most effective for extending the range of a PMMC (Permanent Magnet Moving Coil) ammeter?
Connecting a high resistance in series with the meter coil
Connecting a low resistance shunt in parallel with the meter coil
Connecting a capacitor in parallel with the meter coil
Increasing the number of turns in the coil
Correct answer
Connecting a high resistance in series with the meter coil
In a standard electrodynamometer-type wattmeter, how are the fixed coils and moving coils connected?
Fixed coils in series with the load, moving coil in parallel with the supply
Fixed coils in parallel with the load, moving coil in series with the supply
Both fixed and moving coils are in series with the load
Both fixed and moving coils are in parallel with the supply
Correct answer
Fixed coils in series with the load, moving coil in parallel with the supply
The maximum torque of a three-phase induction motor is unaffected by:
Supply voltage
Rotor resistance
Frequency
Reactance
Correct answer
Supply voltage
In a high-impedance circuit, the voltage across a resistor is measured using a voltmeter with a sensitivity of 20,000 V. How would the reading change if a voltmeter with a 1,000 V sensitivity were used in its place?
The reading would be higher and more accurate
The reading would be lower due to the loading effect
The reading would remain exactly the same
The reading would fluctuate unpredictably
Correct answer
The reading would be higher and more accurate
In the measurement of power using an electrodynamometer wattmeter, the inductance of the pressure coil causes an error. At lagging power factors, this error results in the wattmeter reading being:
Lower than the true power
Higher than the true power
Equal to the true power
Zero
Correct answer
Lower than the true power
The speed of a 4-pole, 50 Hz induction motor is 1440 rpm. What is the rotor current frequency?
2 Hz
50 Hz
4 Hz
1 Hz
Correct answer
2 Hz
Phantom loading is employed for testing energy meters primarily to:
Test the meter at voltages higher than rated
Reduce power consumption during the test
Check the insulation resistance
Increase the starting torque
Correct answer
Test the meter at voltages higher than rated
"Crawling" in a squirrel cage induction motor is characteristically observed at what fraction of the synchronous speed?
\( \frac{1}{3} \)
\( \frac{1}{5} \)
\( \frac{1}{7} \)
\( \frac{1}{9} \)
Correct answer
\( \frac{1}{3} \)