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ECE Objective Questions { Operational Amplifier and Its Applications }

85. In a phase shift oscillator, the frequency determining elements are
A. L and C
B. R, Land C
C. R and C
D. none of the above

86. A wien bridge oscillator uses ____ feedback.
A. only positive
B. only negative both positive and negative
C. none of the above

87. The piezoelectric effect in a crystal is
A. a voltage developed because of mechanical stress
B. a change in resistance because of temperature
C. a change of frequency because of temperature
D. none of the above

88.  If the crystal frequency changes with temperature, we say that crystal has _____ temperature coefficient.
A. positive
B. zero
C. negative
D. none of the above

89. The crystal oscillator frequency is very stable due to of the crystal.
A. rigidity
B. vibrations
C. low Q
D. high Q

90. The application where one would most likely find a crystal oscillator is
A. radio receiver
B. radio transmitter
C. AF sweep generator
D. none of the above

91. An oscillator differs from an amplifier because it
A. has more gain
B. requires no input signal
C. requires no d.c. supply
D. always has the same input

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