Explore topic-wise InterviewSolutions in .

The correct answer is (a) The PEAK to peak VALUE of the voltage

Best EXPLANATION: The OSCILLOSCOPE can measure not only the DC value but also the AC value. The RMS value cannot be measured by the oscilloscope. SIMILARLY, the average value is also not measured. Therefore the peak to peak value of the voltage is measured.

Right option is (d) There is a constant but SMALL PHASE difference between the SIGNALS

To EXPLAIN: X = A sinωt

Y = A sin (ωt-∅t)

Phase difference = ∅t

For ellipse, A1 ≠ A2

For circle, A1 = A2

Hence, there is a constant but small difference between the signals.

Right answer is (b) 3.47 V

To ELABORATE: XC = \(\frac{1}{jCω} = \frac{-J}{2 × 3.14 × 100 × 10^3 × 10 × 10^{-12}}\)

Applying KCL at node,

\(\frac{V_a-10}{100} + \frac{V_a}{100} + \frac{V_a}{500} + \frac{V_a}{-j159}\)

∴ Va = 4.37∠-15.95°.

The correct answer is (b) Electrostatic focusing

To elaborate: A CATHODE RAY OSCILLOSCOPE always USING the focusing technique for its operation. Electromagnetic focusing is used by the Cathode Ray TUBE. However, the Cathode Ray Oscilloscope employs Electrostatic focusing.

Correct answer is (d) A CIRCLE

For explanation: The PATTERN observed on the CRT, when two sinusoidal signals are APPLIED to the X-X and Y-Y PLATES of the CRT are known as Lissajous pattern.

sin φ = \(\frac{y_1}{y_2} = \frac{X_1}{X_2}\)

∴ Screen will show a circle.

Right option is (C) ELLIPSE

For explanation: The pattern observed on the CRT, when two sinusoidal signals are applied to the X-X and Y-Y plates of the CRT are known as Lissajous pattern.

sin φ = \(\FRAC{y_1}{y_2} = \frac{X_1}{X_2}\)

Here, the voltages are unequal and frequencies are EQUAL with a phase SHIFT of 90°. Therefore the Lissajous figure on the screen will be an ellipse.

Correct choice is (d) post-accelerating anode

The best I can explain: The SOURCE of focused and the accelerated ELECTRON BEAM is the electron gun. The electron gun which EMITS electrons forms them into a beam consisting of a heater, a cathode, a grid, a pre-accelerating anode, a focusing anode and an accelerating anode.

Right answer is (c) 0.1 s

For explanation I would SAY: In a dual slope integrating digital VOLTMETER,

\((\frac{t_1}{t_2})\) Vin = Vref

Where, T1 = first integration time = 10 × \(\frac{1}{50}\) = 0.25

But Vin = 1 V and Vref = 2 V

∴ T2 = \(\frac{V_in t_1}{V_{ref}}\) = 0.1 s.

Correct answer is (d) Which RECORDS the VALUE of the quantity measured as well as the electrical and non-electrical quantities as a function of time

For explanation: A recorder is a device which RECORD the value of quantity as it is being measured. It records electrical and non-electrical quantities or relates two signals to each other as a function of time.

Right CHOICE is (c) ACTIVE devices

The explanation is: Curve tracers in a CATHODE Ray Oscilloscope are used for TESTING active devices such as vacuum tubes, transistors and INTEGRATED circuits.

The CORRECT choice is (b) False

To EXPLAIN: A Cathode RAY Oscilloscope, is USED in transmission lines for the measurement of modulation characteristics. It is also used for detecting the standing waves in a transmission line.

The correct answer is (d) displaying cardiograms

For explanation: A Cathode Ray OSCILLOSCOPE, can be used in MEDICAL APPLICATIONS for displaying cardiograms. Cardiograms are used for DIAGNOSING the condition of HEART of a patient. Electromyograms are used for studying the condition of a patient’s muscle.

The correct answer is (a) True

Explanation: A Cathode Ray Oscilloscope, is used for observing B-H curves, P-V DIAGRAMS, ETC. A CRO is also used in various transducers for the MEASUREMENT of strain, pressure and temperature.

Correct answer is (C) a wide range of frequencies

The explanation: By making USE of a Cathode Ray OSCILLOSCOPE, a wide range of frequencies can be measured. The radio frequency, AUDIO frequency and intermediate frequency signals can be measured by making use of a CRO.

The correct answer is (d) nm

To explain: In Real time sampling, a trigger event can be USED to CAPTURE as MUCH as nm samples. The waveform is then DISPLAYED on a digital storage OSCILLOSCOPE.

Correct answer is (a) FS/4

The best EXPLANATION: In Real time sampling, the 3 dB bandwidth is set to fs/4 with an overshoot of 5%. Here fs is the sampling FREQUENCY.

The correct option is (c) large MEMORY and fast sampling

Explanation: In REAL time sampling, a higher sampling rate is required to capture long time interval signal capturing. Large memory and a fast sampling rate are the CHARACTERISTIC FEATURE of real time sampling.

The correct choice is (b) Fs ≥ 2fmax

Easy EXPLANATION: NYQUIST criteria STATES that the sampling rate is TWICE the maximum frequency. It is GIVEN by the relation.

Fs≥2fmax

where, Fs is the sampling rate

fmax is the maximum frequency.

Right choice is (a) True

Easiest explanation: In REAL time SAMPLING, the BANDWIDTH is only ¼ of the ACTUAL value. As a result to increase the bandwidth, fast sample rate DIGITIZERS and memory are required which are very expensive.

Right ANSWER is (d) one

To explain: In SEQUENTIAL repetitive sampling, one SAMPLE is CAPTURED at a controlled time delay of tds. After each point is captured, the delay is increased by a small amount tse/sub>.

Correct ANSWER is (C) Sequential repetitive sampling

Easiest explanation: In Sequential repetitive sampling, pretrigger information cannot be captured. And the pretrigger view is LOST. It can be used only in MICROWAVE digital OSCILLOSCOPE as a result.

The correct answer is (B) False

Easiest explanation: For an oscilloscope with a bandwidth of 20 to 50 GHz, a HIGH speed network setting is required. This is achieved through the means of the sequential REPETITIVE SAMPLING.

The correct ANSWER is (a) 3

To explain: In a DIGITAL storage oscilloscope, there are three methods in which a digital SIGNAL can be captured and stored. They are as follows:

i) Real time sampling

ii) Random REPETITIVE sampling

iii) Sequential repetitive sampling.

Correct option is (c) directly proportional

The EXPLANATION: Frequency is inversely proportional to the time period of any GIVEN signal.

F = ^1⁄t

where, f is the frequency

T is the time period.

The correct choice is (c) T = number of DIVISIONS occupied by 1 cycle×(^TIME⁄division)

The explanation: The time period of a waveform is OBTAINED by USING the relation,

T=number of divisions occupied by 1 cycle×(^time⁄division).

Right ANSWER is (a) True

To explain: Generally, a CRO is a voltage measuring DEVICE. Current is MEASURED by passing current through a known value of resistance. Voltage across the resistance is displayed on the SCREEN of the CRO.

Right choice is (b) VRMS = \(\FRAC{V_m}{\sqrt{2}}\)

The explanation: The r.m.s value of VOLTAGE is GIVEN by the RELATION,

Vrms = \(\frac{V_m}{\sqrt{2}}\)

where, Vrms is the r.m.s value of voltage

Vm is the amplitude of the voltage.

Right choice is (a) many characteristics of a signal can be measured

To EXPLAIN I WOULD say: Through the means of a Cathode Ray OSCILLOSCOPE, most of the characteristics of an INPUT signal can be measured. Properties of a signal can be studied as well.

Correct answer is (a) 3 MODES

Best explanation: In a digital STORAGE oscilloscope, there are three modes of OPERATION. They are as follows:

• Store

• Roll

• Hold or SAVE.

Correct CHOICE is (d) through a MICROPROCESSOR

Best explanation: In a digital storage OSCILLOSCOPE, the data is displayed by passing it through a microprocessor which processes the data and displays the waveform ONTO a screen.

Right answer is (C) A/D converter

To explain: In a DIGITAL storage oscilloscope, the analog signal is DIGITIZED by making USE of an analog to digital converter. After DIGITIZING the waveform is loaded into a computer and can be analyzed.

The CORRECT CHOICE is (a) low

Easy explanation: In a digital storage oscilloscope, the POWER REQUIRED by the memory is less. It can be supplied through the MEANS of a small battery.

The CORRECT ANSWER is (d) conventional

The explanation is: A digital storage oscilloscope makes use of a conventional cathode RAY TUBE. As a result, the COST is reduced.

The CORRECT answer is (c) digital form

Easy EXPLANATION: The WAVEFORM to be studied is STORED in digital form in the digital storage oscilloscope. It is digitized and stored in a digital memory.

Right option is (B) False

Easiest EXPLANATION: In a digital storage oscilloscope, the MEMORY can store data as long as REQUIRED without degradation. It makes use of complex signal processing techniques through HIGH speed digital signal processing.

The CORRECT option is (a) uses DIGITAL storage

To ELABORATE: The DISADVANTAGE of a analog storage OSCILLOSCOPE is overcome in a digital storage oscilloscope. The unreliable storage method in a analog storage oscilloscope is overcome in a digital storage oscilloscope. The digital storage oscilloscope makes use of digital storage for the memory.

The correct CHOICE is (c) many beams are PRODUCED

To EXPLAIN: In a multi-beam OSCILLOSCOPE, several beams are produced from a single tube. Each system is made up of a separate set of vertical deflection plates and a common time base system.

The CORRECT choice is (B) False

To explain I would say: In a dual BEAM OSCILLOSCOPE, the sweep rates are different for different channels. As a result the size and weight of the oscilloscope is INCREASED. A dual beam oscilloscope has a separate time-base for different channels.

The CORRECT answer is (d) CHANNEL A or B

Best explanation: In a dual beam OSCILLOSCOPE, the SWEEP generator is triggered internally by means of EITHER the channel A signal or the channel B signal.