Most Competitive Oscilloscopes ( Electrical Measurements ) MCQs – Electrical Measurements MCQs
Latest Electrical Measurements MCQs
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Electrical Measurements MCQs – Oscilloscopes ( Electrical Measurements ) MCQs
The most occurred mcqs of Oscilloscopes ( ) in past papers. Past papers of Oscilloscopes ( Electrical Measurements ) Mcqs. Past papers of Oscilloscopes ( Electrical Measurements ) Mcqs . Mcqs are the necessary part of any competitive / job related exams. The Mcqs having specific numbers in any written test. It is therefore everyone have to learn / remember the related Oscilloscopes ( Electrical Measurements ) Mcqs. The Important series of Oscilloscopes ( Electrical Measurements ) Mcqs are given below:
Oscilloscope
1. CRO stands for __________
a) Cathode Ray Oscilloscope
b) Current Resistance Oscillator
c) Central Resistance Oscillator
d) Capacitance Resistance Oscilloscope
Answer: a
Explanation: Cathode Ray Oscilloscope (C.R.O) is basically used for the measurement of the amplitude of periodic and non periodic signals as a function of time.
2. C.R.O gives __________
a) actual representation
b) visual representation
c) approximate representation
d) incorrect representation
Answer: b
Explanation: Cathode Ray Oscilloscope is used as universal laboratory equipment. It provides a visual representation of time varying signals. It is an important equipment in the development of electronic circuits.
3. Oscilloscope is __________
a) a ohmmeter
b) an ammeter
c) a voltmeter
d) a multimeter
Answer: c
Explanation: Oscilloscope is basically a voltmeter. It employs the movement of an electronic gun assembly with respect to a fluorescent screen. The screen produces the movement of the visible spot.
4. Electron beam is deflected in __________
a) 1 direction
b) 4 directions
c) 3 directions
d) 2 directions
Answer: d
Explanation: The electron beam in an oscilloscope can be deflected in two directions, namely the horizontal (x-direction) and the vertical (y-direction). Two dimensional displays are produced as a result.
5. CRO is a __________
a) fast x-y plotter
b) slow x-y plotter
c) medium x-y plotter
d) not a plotter
Answer: a
Explanation: CRO is basically a fast x-y plotter. The x and y axes can be used to understand the variation in the magnitude of one voltage with respect to another voltage signal.
6. CRO can’t display microseconds time.
a) True
b) False
Answer: b
Explanation: CRO is a fast x-y plotter and displays periodic signals with time periods of the order of a few microseconds and even nanoseconds.
7. CRT is the heart of CRO.
a) True
b) False
Answer: a
Explanation: CRT stands for Cathode Ray Tube. It generates electron beam, accelerates and deflects the beam. It thus forms the heart of the CRO.
8. Typically oscilloscope represents __________
a) current and time
b) resistance and time
c) voltage and time
d) power and time
Answer: c
Explanation: In an oscilloscope typically the horizontal or x-axis represents the time while the vertical or y-axis represents the variation in the magnitude of the input signal.
Cathode Ray Tube
1. Electron gun section ________
a) provides sharp beam
b) provides poorly focused beam
c) doesn’t provide any beam
d) provides electrons only
Answer: a
Explanation: In a cathode ray tube, the electron gun section gives a sharply focussed beam of electrons. They are focused on the fluorescent coated screen.
2. Control grid is given ________
a) positive voltage
b) negative voltage
c) neutral voltage
d) zero voltage
Answer: b
Explanation: Grid controls the amount of electrons falling on the fluorescent screen of a cathode ray tube. Cathode ray tube is provided with a negative voltage with respect to the cathode as a reference.
3. What determines light intensity in a CRT?
a) voltage
b) current
c) momentum of electrons
d) fluorescent screen
Answer: c
Explanation: Momentum of the electrons gives the intensity or brightness of the light emitted from the fluorescent screen due to electron bombardment. It is given as the product of the no of electrons and their speed.
4. Effect of negative voltage to the grid is ________
a) no force
b) a gravitational force
c) an attractive force
d) a repulsive force
Answer: d
Explanation: Since the electron is negatively charged, application of a negative voltage to the control grid produces a repulsive force.
5. Electron beam diverges.
a) True
b) False
Answer: a
Explanation: Similar charges on electrons lead to a repulsion. As a result the electron beam diverges as it contains many electrons. Electrostatic force is applied between the focussing anodes in order to compensate the repulsive force.
6. Focusing and accelerating anodes are ________
a) rectangular
b) cylindrical
c) spherical
d) square
Answer: b
Explanation: Focusing and accelerating anodes in a cathode ray tube are essentially cylindrical in nature. Each electrode has a small opening at the centre with a co-axial tubular axis.
7. Deflection system of a CRT consists of ________
a) 4 plates
b) 6 plates
c) 2 plates
d) 8 plates
Answer: c
Explanation: Cathode ray tube consists of two sets of plates that are parallel in nature. They are referred to as horizontal and vertical deflection plates. One of the plates is set to ground potential.
8. Horizontal deflection is given by ________
a) x = Kx
b) x = Vx
c) x = 1
d) x = Kx Vx
Answer: d
Explanation: In a cathode ray tube the horizontal deflection is given by,
x = Kx Vx
where, Kx is the constant of proportionality
x is the horizontal deflection
Vx is the horizontal deflecting voltage.
9. Vertical deflection is given by ________
a) y = Ky Vy
b) y = Ky
c) x = 1
d) y = Vy
Answer: a
Explanation: In a cathode ray tube the vertical deflection is given by,
y = Ky Vy
where, Ky is the constant of proportionality
y is the vertical deflection
Vy is the vertical deflecting voltage.
Basic Principle of Signal Display
1. What provides a periodic voltage waveform?
a) sweep generator
b) voltmeter
c) oscillator
d) amplifier
Answer: a
Explanation: Sweep generator provides a periodic voltage waveform in an oscilloscope. As the waveform resembles the teeth of a hacksaw it is known as a sawtooth waveform.
2. Visible spot must be moved in _______
a) two directions
b) one direction
c) three directions
d) four directions
Answer: b
Explanation: Sweep voltage must be brought to zero once it reaches its maximum value. The visible spot must be moved in a single direction only. Return sweep will trace back the signal in a reverse direction.
3. Spot is displayed only when _______
a) frequencies are different
b) frequencies are zero
c) frequencies are same
d) voltage is high
Answer: c
Explanation: When the sweep frequency and the signal frequency are same or integral multiple of each other, visible spot is displayed on the screen of the cathode ray oscilloscope.
4. What is done to make the trace horizontal?
a) negative voltage is applied
b) positive voltage is applied
c) no voltage is applied
d) voltage is synchronised
Answer: d
Explanation: The trace is made stationary by synchronising the sawtooth voltage with the magnitude of the signal that is applied to the vertical input.
5. A single cycle appears on the screen when _______
a) sweep and signal frequencies are equal
b) sweep and signal frequencies are not equal
c) sweep and signal frequencies are zero
d) sweep frequency is greater than signal frequency
Answer: a
Explanation: Many cycles are present on the screen when the sweep frequency is lower than the signal frequency. Only a single cycle appears on the screen when the sweep and signal frequencies are equal.
6. Sinusoidal voltage is not observed on the screen.
a) True
b) False
Answer: b
Explanation: Application of a sinusoidal voltage to the y terminal and the internally produced sawtooth voltage to the x terminal results in the shifting of the sawtooth voltage in terms of magnitude. Finally a sinusoidal waveform is observed on the screen.
7. What is the flyback period?
a) voltage is very high
b) current is very low
c) voltage is zero
d) current is very high
Answer: c
Explanation: During the flyback period, voltage suddenly drops to zero from a certain value.
8. During trace time, voltage is decreasing with time.
a) True
b) False
Answer: b
Explanation: The electron beam moves linearly along the horizontal direction during the trace time. The voltage Vx increases linearly with respect to time Tr during the instant of the trace period.
9. Light produced in a screen is _______
a) disappears immediately
b) does not disappear at all
c) is not visible to the eye
d) disappears slowly
Answer: d
Explanation: When the magnitude of the applied voltage reduces to zero, the light produced on the screen due to the bombardment of electrons does not disappear immediately and reduces in terms of intensity slowly.
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
Explanation: 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
Explanation: 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
Explanation: 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
Explanation: 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
Explanation: 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
Explanation: 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
Explanation: 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
Explanation: 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
Explanation: 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.
Delay Line
1. CRO uses __________
a) 2 delay lines
b) 3 delay lines
c) 4 delay lines
d) 5 delay lines
Answer: a
Explanation: Cathode Ray Oscilloscope uses two delay lines. They are as follows:
Lumped parameter delay line and
Distributed parameter delay line.
2. T section in a delay circuit of CRO acts as ________
a) high pass filter
b) low pass filter
c) band pass filter
d) band reject filter
Answer: b
Explanation: In the delay circuit of a CRO, T section is present in the lumped parameter delay line. The T section acts as a low pass filter having a cut off frequency as,
.
3. Lumped parameter delay line consists of________
a) RC networks
b) RL networks
c) LC networks
d) Resistive networks
Answer: c
Explanation: In the delay line circuit of a Cathode Ray Oscilloscope, the lumped parameter delay line is made of several cascaded LC networks. They are known as T sections.
4. Delay for the T section is given by ________
a) ts = 1⁄fc
b) ts = 1
c) ts = 1⁄π
d) ts = 1⁄πfc
Answer: d
Explanation: In the T section of the lumped parameter delay in a delay line circuit of the CRO the delay is given by the relation
ts = 1⁄πfc
ts = delay for a single circuit
td = total delay
n = number of T sections.
5. Distributed parameter delay line is a transmission line.
a) True
b) False
Answer: a
Explanation: The delay line circuit consists of distributed parameter delay as well as lumped parameter delay. The distributed parameter delay is basically a transmission line with a coil wound on a helix mandrel.
6. Inductance does not affect a transmission line.
a) True
b) False
Answer: b
Explanation: The inductance of the transmission line in a distributed parameter delay line can be increased by winding the inner conductor of the helix onto a ferromagnetic core.
7. Typical values for a distributed parameter delay line are ________
a) Zo = 10 Mῼ and td = 10 nsec/m
b) Zo = 1 kῼ and td = 500 nsec/m
c) Zo = 1000 ῼ and td = 180 nsec/m
d) Zo = 100 Gῼ and td = 275 nsec/m
Answer: c
Explanation: For the distributed parameter delay line in a delay line circuit the typical parameters are the characteristic impedance which is Zo = 1000 ῼ and the delay time which is td = 180 nsec/m.
8. What is the effect of the signal delay on the sweep generator?
a) no effect
b) input increases in magnitude
c) output doesn’t get any delay
d) output gets sufficient delay
Answer: d
Explanation: When the signal is delayed, the sweep generator’s output gets sufficient time in order to reach the horizontal plates before the signal passes over to the vertical deflection plates.
Front Panel Controls of CRO
1. Front panel of a CRO has _________
a) 4 sections
b) 8 sections
c) 15 sections
d) 20 sections
Answer: a
Explanation: A simple Cathode Ray Oscilloscope has the following four sections:
i) Basic controls
ii) Vertical section
iii) Horizontal section
iv) Z axis intensity control.
2. What is the role of the intensity section in a CRO?
a) decreases the light intensity
b) controls light intensity
c) increases the light intensity
d) keeps the light intensity zero
Answer: b
Explanation: In a Cathode Ray Oscilloscope the intensity section controls the brightness or intensity of the light beam produced by the bombardment of electrons on the fluorescent screen.
3. What is the role of the focus section in a CRO?
a) increases the focus
b) decreases the focus
c) controls sharpness
d) maintains the focus zero
Answer: c
Explanation: In a Cathode Ray Oscilloscope the focus section controls the sharpness of the visible spot on the screen. By varying the voltage applied to the focusing anodes, visible spot on the screen is focused sharply.
4. What is the role of astigmatism in a CRO?
a) increases the intensity
b) used for voltage stability
c) diminishes the intensity
d) focus control
Answer: d
Explanation: In a Cathode Ray Oscilloscope the astigmatism forms another set of focus control. A sharp spot can be obtained by the combination of focus control and astigmatism.
5. What is the role of scale illumination in a CRO?
a) measurement
b) illumination
c) sharpness
d) stability
Answer: a
Explanation: In a Cathode Ray Oscilloscope the scale illumination is basically used for the purpose of measurement. It basically illuminates the scale and as a result the reading can be clearly seen.
6. What is the role of an invert in a CRO?
a) inverts the output
b) inverts the input
c) attenuates the input
d) magnifies the input
Answer: b
Explanation: In a Cathode Ray Oscilloscope the invert control section is used for the purpose of inverting the input signal. It basically multiplies the input signal by a factor of -1.
7. X10 in a CRO means ________
a) one tenth
b) control knob
c) 10 times as normal
d) attenuate the voltage by 10 times
Answer: c
Explanation: In a Cathode Ray Oscilloscope X10 indicates that gain of the vertical amplifier is made 10 times that of the normal value. When the X10 switch is turned ON, scope of the CRO is et to 0.05 V/cm.
8. Position knob in a CRO indicates ________
a) voltage position only
b) time position only
c) current position only
d) any pattern’s position
Answer: d
Explanation: In a Cathode Ray Oscilloscope the position knob is used for indicating the position of any pattern on the screen. The pattern can be shifted vertically upwards or downwards.
9. Alternate is used to shift the inputs.
a) True
b) False
Answer: a
Explanation: In a Cathode Ray Oscilloscope the alternate knob is used to transition between the two different input signals. Using the vertical position control, the traces of the two input signals are separated vertically.
Time Base
1. Time domain oscilloscopes require ___________
a) sweep generator
b) oscillator
c) amplifier
d) rectifier
Answer: a
Explanation: Time domain oscilloscopes need a sweep generator. The sweep generator must be a linear function of time for the x-axis display.
2. What is time base generator?
a) time measuring device
b) generator
c) voltage generation device
d) current generation device
Answer: b
Explanation: In a Cathode Ray Oscilloscope, a generator that produces a waveform required for the movement of the visible spot horizontally is known as the time base generator.
3. Linear sweep moves spot __________
a) top to bottom
b) right to left
c) left to right
d) bottom to top
Answer: c
Explanation: In a Cathode Ray Oscilloscope, a linear sweep is used to move the visible spot from left to right direction. The movement of the spot from right to left direction is not visible.
4. Time base generator controls __________
a) intensity of light
b) current direction
c) voltage magnitude
d) spot movement
Answer: d
Explanation: In a Cathode Ray Oscilloscope, the time base generator controls the rate at which the visible spot moves across the screen. Using the front panel controls this rate can be modified.
5. Time dependent waveforms need x-axis for calibration.
a) True
b) False
Answer: a
Explanation: In a Cathode Ray Oscilloscope, the time dependent waveforms need x-axis for calibration. It is calibrated as the time axis.
6. Sweep generator works on the principle of __________
a) inductor
b) capacitor
c) resistor
d) diode
Answer: b
Explanation: In a Cathode Ray Oscilloscope, the sweep generator basically works on the principle of a capacitor. It generates linear rise time voltages by making use of the charging characteristics of a capacitor.
7. Left to right visibility of the spot is ensured by __________
a) linear waveform
b) linear ramp waveform
c) sinusoidal waveform
d) unit step waveform
Answer: c
Explanation: In the time base generator, a linearly increasing ramp waveform that decreases to zero within a very short time span is used to make sure that the spot is only visible from left to right direction.
8. Time base generator circuit resembles a __________
a) regulator
b) rectifier
c) amplifier
d) oscillator
Answer: d
Explanation: The time base generator circuit is basically a relaxation oscillator. It generates a saw tooth waveform. A bootstrap technique allows linearity but is very expensive.
9. Sweep generator is a time base generator.
a) True
b) False
Answer: a
Explanation: In a Cathode Ray Oscilloscope the sweep base generator produces the movement of the spot on the screen. It acts as the time base for the waveforms and as a result it is known as a time base generator.
Principle of Time Base Generator
1. What is hold off time in a CRO?
a) time to start a ramp
b) time to end a ramp
c) time to start a unit step
d) time to end a unit step
Answer: a
Explanation: In a Cathode Ray Oscilloscope, the trigger circuit applies the pulse as soon as the cycle ends. The hold off time in a time base generator is defined as the time taken for the ramp signal so as to stabilise the flyback circuitry.
2. What is the wait time in a CRO?
a) time to deactivate time base generator
b) time to activate time base generator
c) time from input to output
d) time from output to input
Answer: b
Explanation: In a Cathode Ray Oscilloscope, the trigger circuit produces a trigger pulse. The pulse must exceed a certain reference threshold level in order to activate the time base generator. This is known as trigger threshold.
3. A trigger circuit is ___________
a) is used for triggering the input
b) is used for triggering the output
c) used with time base generator
d) used as a oscillator
Answer: c
Explanation: In a Cathode Ray Oscilloscope, the trigger circuit is basically used for triggering the time base generator. It triggers the time base generator and produces a ramp signal.
4. Time base generator takes certain time to begin a new cycle.
a) True
b) False
Answer: a
Explanation: After the end of a cycle of sweep and retrace, the time base generator takes certain amount of time to commence a new cycle. This time can be divided into two parts:
i) Hold off time and ii) Waiting time.
5. After hold off time, the time base generator is activated immediately.
a) True
b) False
Answer: b
Explanation: As a result of trigger threshold crossing the time base generator doesn’t immediately get activated after the hold off time. This time is known as the waiting time wherein the triggering pulses cross the trigger threshold.
6. A time base should have _________
a) non-linearity
b) ramp relationship
c) linearity
d) unit step relationship
Answer: c
Explanation: In a Cathode Ray Oscilloscope, a time base generator must have a linear relationship. Linearity of the order of more than 1 % across the cathode ray tube can be obtained by making use of a time base generator.
7. The horizontal amplifier in a CRO can be expanded by _________
a) 5 times
b) 15 times
c) 30 times
d) 10 times
Answer: d
Explanation: In a Cathode Ray Oscilloscope, the horizontal amplifier can be expanded by up to 10 times. This allows a division of 1nsec display for very high speed transient waveforms.
8. Sweep rate is controlled by a _________
a) capacitor
b) resistor
c) diode
d) inductor
Answer: a
Explanation: In a Cathode Ray Oscilloscope, the sweep rate is controlled by a capacitor. This is done through means of the charging current flowing through the capacitor.