Electrical Measurements & Measuring Instruments Multiple Choice Questions on “Simple Oscilloscope”.
1. What is the role of CRT?
a) to emit electrons
b) to emit protons
c) to emit neutrons
d) to emit alpha particles
Answer: a
Clarification: Cathode ray tube forms the heart of a C.R.O. It is used to emit electrons so as to strike the phosphor screen to produce a spot for the visual display of the signals.
2. Input signals are amplified using ___________
a) rectifier
b) amplifier
c) oscillator
d) op amp
Answer: b
Clarification: Vertical amplifier is used in a cathode ray tube to amplify the input signals. Magnitude of the input signal is weak and not sufficient enough to give deflection on the screen.
3. Amplifier stage is ___________
a) half band
b) full band
c) wide band
d) narrow band
Answer: c
Clarification: Wide band amplifiers are generally used to amplify the input signals. The whole band of frequency to be measured must be passed faithfully by making use of a wide band amplifier.
4. Role of an attenuator is ___________
a) to boost the signal
b) to distort the signal
c) to remove noise
d) to improve the operation
Answer: d
Clarification: When we need to measure very high voltage signals, attenuator stages are used. This is done in order to bring the signal level within the range of operation of the amplifier.
5. Amplifier is multiple stage in a CRO.
a) True
b) False
Answer: a
Clarification: A Cathode Ray Tube essentially consists of multiple stages of amplifiers with a overall fixed sensitivity. Amplifier is designed for stability and required bandwidth very easily due to the fixed gain.
6. Input stage in the amplifier consists of ___________
a) oscillator
b) attenuator
c) rectifier
d) op amp
Answer: b
Clarification: The amplifier stage of a Cathode Ray Tube essentially consists of an attenuator stage. It is followed by a FET source follower. The input impedance is very high.
7. Phase inverter is used in an amplifier in the CRO because ___________
a) phase inversion is needed
b) no phase inversion is needed
c) it is needed to operate a push pull
d) it provides voltage stability
Answer: c
Clarification: In a Cathode Ray Oscilloscope, phase inverter is typically used for operating a push pull amplifier. It provides two antiphase output signals in order to operate the push pull amplifier.
8. BJT is used in the amplifier stage.
a) True
b) False
Answer: a
Clarification: A BJT emitter follower is used in the amplifier stage after the FET in order to provide impedance matching to the output of the FET. With respect to the input of the phase-inverter.
9. Why is a delay line used in a CRO?
a) to boost the signal
b) to distort the signal
c) to provide signal delay
d) for stability
Answer: c
Clarification: Delay line is used in a Cathode Ray Oscilloscope so as to delay the signal for some time. If the delay line is not used then a part of the signal is lost. A delay line circuit is used for this purpose.
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