636. If the gain of an open loop system is doubled, the gain margin
A. Is not affected
B. Gets double
C. Becomes half
D. Becomes one-fourth
Ans.: C
637. An all pass network imparts only
A. Negative phase to the input
B. Positive phase to the input
C. +/–90 degree phase shift to the input
D. +/–180 degree phase shift to the input
Ans.: D
638. An ON-OFF controller is
A. P controller
B. Integral controller
C. Non-linear controller
D. PID controller
Ans.: C
639. The transfer function of a phase lead controller is (1 + 3Ts) / (1 + Ts). The maximum value of phase provided by this controller is
A. 90
B. 60
C. 45
D. 30
Ans.: D
640. The thermal time constant is the time
A. To reach the final steady temperature if the initial rate of increase of
temperature were maintained constant
B. To reach 63% of final steady temperature
C. To reach 66.66% of final steady temperature
D. To reach half of the final steady temperature
Ans.: B
641. Which of the following circuit will have no transients?
A. Pure resistive circuit
B. L-C Circuit
C. R-L-C Circuit
D. R-L Circuit
Ans.: A
642. A conductor of length 100 cm moves right angles to a magnetic field of flux density of 2 wb/sq.m. with the velocity of 25 m/second. The induced emf in the conductor will be
A. 25 volts
B. 50 volts
C. 75 volts
D. 100 volts
Ans.: B
643. Which of the following devices are required to measure three phase balanced power?
A. One watt meter
B. One watt meter and one voltage transformer of 1 : 1 ratio
C. One watt meter and two voltmeters
D. None of the above
Ans.: A
644. The sensitivity of an instrument is
A. The smallest increment in the input that can be detected with certainty
B. The largest input change to which the instrument fails to respond
C. Ratio of the change in the magnitude of the output to the corresponding change
in the magnitude of the input
D. Closeness of the output values for repeated application of a constant input
Ans.: C
645. Potentiometer sensitivity can be increased by
A. Decreasing current in the potentiometer wire
B. Increasing the length of the potentiometer wire
C. Decreasing the length of the potentiometer wire
D. Replacing the cell by a regulated power supply
Ans.: B
646. Low resistance is measured with
A. De Sauty’s bridge
B. Maxwell’s bridge
C. Kelvin’s double bridge
D. Wien bridge
Ans.: C
647. Which bridge is used to determine frequency?
A. Anderson bridge
B. De Sautys bridge
C. Wien bridge
D. Campell’s bridge
Ans.: C
648. The core of a moving iron instrument is made up of permalloy to
A. Increase sensitivity
B. Reduce temperature effect
C. Reduce effect of stray magnetic field
D. Reduce the size of the instrument
Ans.: A
649. Accuracy is defined as
A. The measure of consistency of the readings
B. Closeness with which an instrument reading approaches the true value of the
quantity being measured
C. The smallest measurable input change
D. The ratio of the input to output
Ans.: B
650. If three amplifiers having the same bandwidth are cascaded, the bandwidth of the resulting amplifier will be
A. Better than that of each stage
B. Worse than that of each stage
C. Same as that of each stage
D. None of the above
Ans.: B