Q. 496 If the absolute voltage gain of an amplifier is 100 then its decibel gain is
A. 20 dB
B. 10 dB
C. 40 dB
D. 60 dB
Ans.: C
Q.497 In an amplifier coupling capacitor is used to
A. Math the impedance
B. Prevent DC mixing with output
C. Control frequency
D. Limit the bandwidth
Ans.: B
Q.498 The maximum efficiency of class B amplifier
A. 50%
B. 78.5%
C. 35%
D. 100%
Ans.: B
Q.499 The induced e.m.f (electromagnetic field) in the transformer secondary will depend on
A. frequency of supply only
B. number of turns in secondary only
B. Frequency and flux in core
D. Frequency, number of secondary turn and flux in the core
Ans.: D
Q.500 The short circuit test in the transformer is performed to determine
A. Iron loss
B. Hysteresis loss
C. Copper loss at any load
D. Eddy current loss
Ans.: C
Q.501 Which of the following electrical machine has the highest efficiency
A. D.C Generator
B. A.C Generator
C. Transformer
D. Induction Motor
Ans.: C
Q.502 The eddy current losses in the transformer will be reduced if
A. The number if turns in the primary winding are reduced
B. The number of turns in the secondary winding is reduced
C. Laminations are thick
D. Laminations are thin
Ans.: D
Q.503 The induced emf in a dc machine is proportional to
A. Field flux only
B. Speed of armature
C. Armature current
D. Field flux and speed of armature
Ans.: D
Q. 504 In an LC series circuit at resonance, the
A. Impedance is maximum
B. Voltage across the capacitor C is maximum
C. current is maximum
D. Current is minimum
Ans.: C
Q.505 A pure inductance when connected across 230V, 50Hz supply consumes 40W. This consumption is
A. due to reactance of inductor
B. Due to current flowing through the inductor
C. Due big size of inductor
D. Statement is false
Ans.: D
Q.506 The stator winding of an induction motor can be designed for
A. Any number of pole
B. Any even number of pole
C. Any odd number of poles
D. Only four pole
Ans.: B
Q.507 Slip rings of a phase wound induction motor are made of
A. Wood
B. Cast Iron
C. Steel
D. Copper
Ans.: D
Q.508 The value of resistor having Red-Red-Red-Gold color band is
A. 220 ohm± 10%
B. 2.2 k-ohm ± 5%
C. 120 ohm ± 50%
D. 220 ohm ± 20%
Ans.: B
Q.509 An ideal current source supplies a current of 200 m/a to a load of 1 k-ohm when the load is changed to 100 ohm the load current will be
A. 200 mA
B. 2000 mA
C. 20 mA
D. None of above
Ans.: A
Q.510 In closed loop control system, with positive value of feedback gain, the overall gain of the system will be
A. Decrease
B. Increase
C. Unaffected
D. none of the above
Ans.: A