21. CRO (Cathode Ray Oscilloscope) CANNOT be used to measure _______.
Frequency
Phase
Power
Voltage
Answer.3. Power
Explanation:
CRO is a very versatile instrument in the laboratory for the measurement of voltage, current, frequency, and phase angle of any electrical quantity.
We cannot directly measure power by using CRO.
The current is measured indirectly by measuring the voltage drop across an impedance.
A Lissajous figure is a pattern that is displayed on the screen when sinusoidal signals are applied to both horizontal & vertical deflection plates of CRO.
These are used to measure the frequency of the given signals and the phase difference between the signals.
From the shape of the Lissajous pattern displayed on the CRO screen information about relative phases of signals and the frequency ratio of signals can be determined.
It is not used for precise measurement; it depends on the type of signal.
If one frequency is an integral multiple (harmonic of the other, the pattern will be steady. If not, the figure will not be stationary.
22. The Lissajous pattern is used to measure ___________ using an oscilloscope.
Power
Current
Voltage
Frequency
Answer.4. Frequency
Explanation:
Lissajous figures are used for the measurement of frequency and phase difference.
When horizontal deflection plates and vertical deflection plates of CRO (Cathode Ray Oscilloscope) are connected to two sinusoidal voltages, the patterns that appear at the CRO screen are called the Lissajous pattern
The Lissajous pattern obtained in a CRO depends upon frequency, amplitude, and phase relationship
The patterns used to measure phase and frequency with a cathode ray oscilloscope are called Lissajous patterns.
23. The instrument used to measure current is called
Wattmeter
Ohmmeter
Energy meter
CRO
Answer.4. CRO
Explanation:
CRO is a very versatile instrument in the laboratory for the measurement of voltage, current, frequency, and phase angle of any electrical quantity.
A Lissajous figure is a pattern that is displayed on the screen when sinusoidal signals are applied to both horizontal & vertical deflection plates of CRO.
These are used to measure the frequency of the given signals and the phase difference between the signals.
24. An oscilloscope indicates ___________
Peak to peak value of the voltage
DC value of the voltage
RMS value
Average value
Answer.1. Peak to peak value of the voltage
Explanation:
CRO is a very versatile instrument in the laboratory for the measurement of voltage, current, frequency, and phase angle of any electrical quantity. It indicates the peak to the peak value of voltage.
25. The function of the recorder in CRO is ______
Indicating instrument which displays a time-varying signal
Record the value of a quantity as it is being measured
Records electrical quantities
Records non-electrical quantities
Answer.2. Record the value of a quantity as it is being measured
Explanation:
A recorder is a device whose function is to record the value of a quantity as it is being measured.
Recording preserves the experimental data in a manageable and usable form.
A recording system is very useful in industries as (i) it preserves information that could be obtained at an instant from indicating instruments and (ii) it gives information about waveforms and transient behavior or phase relations in different parts of a circuit.
26. The two inputs of a CRO are fed with two stationary periodic signals. The figure changes from ellipse to circle and back to ellipse with its major axis changing orientation slowly and repeatedly. The following inference can be made from this.
The signals are not sinusoidal in nature
The amplitudes of the signals are very close but not equal
The signals are sinusoidal with their frequencies very close but not equal
There is a constant but small phase difference between the signals
Answer.4. There is a constant but small phase difference between the signals
Explanation:
When the Lissajous pattern is converted from ellipse to circle & circle to again ellipse with the major axis is changed then there is a constant but small phase difference between the signal.
27. The role of CRT is to ______
Emit electrons
Emit protons
Emit neutrons
Emit alpha particles
Answer.1. Emit electrons
Explanation:
A cathode-ray tube is a device that uses a beam of electrons in order to produce an image on a screen. The Role of CRT is to Emit Electron. The heart of the major component of the oscilloscope is the cathode ray tube (CRT). The rest of the CRO consists of circuitry to operate the CRT.
28. The delay line used in a CRO to ______
Boost the signal
Distort the signal
Provide signal delay
For stability
Answer.3. Provide signal delay
Explanation:
A delay line is placed between the output of the vertical amplifier and the y input of the cathode ray tube, to delay the incoming unknown signals.
The purpose of the delay line is to synchronize unknown signals with sweep signals such that the complete signal portion will be displayed without any loss.
29. Delay line is essential in a CRO, to ensure that
Vertical signal starts after the retrace period of sweep signal
The sweep reaches the horizontal plates before the desired signal under consideration
Initial part of signal to be observed is not lost
All of the above
Answer.3. Initial part of signal to be observed is not lost
Explanation:
A delay line is placed between the output of the vertical amplifier and the y input of the cathode ray tube, to delay the incoming unknown signals.
The purpose of the delay line is to synchronize unknown signals with sweep signals such that the complete signal portion will be displayed without any loss.
30. In cathode Ray oscilloscope in vertical amplifier ______ is used in amplifier stage.
JFET
BJT
Diode
Zener Diode
Answer.2. BJT
Explanation:
The vertical amplifier consists of several stages, with fixed overall sensitivity or gain expressed in V/div.
The advantage of fixed gain is that the amplifier can be more easily designed to meet the requirements of stability and Bandwidth.
The vertical amplifier is kept within its signal handling capability by proper selection of the input attenuator switch.
The first element of the pre-amplifier is the input stage, often consisting of a FET source follower whose high input impedance isolates the amplifier from the attenuator.
This FET input stage is followed by a BJT emitter follower, to match the medium impedance of FET output with the low impedance input of the phase inverter.
