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# Multiple choice question for engineering

## Set 1

1. Electronic switch is used in a dual trace oscilloscope.
a) True
b) False

Answer: a [Reason:] By using a single CRT gun, two signals can be displayed on the screen simultaneously by means of an electronic switch.

2. Signals are applied to ___________
a) input
b) gain control stage
c) output
d) capacitor

Answer: b [Reason:] In a dual trace oscilloscope, the signals are applied to the gain control as well as the gate control stage.

3. What adjusts the amplitudes of the signals A and B?
a) L1 and L2
b) C1 and C2
c) R1 and R2
d) Oscillator

Answer: c [Reason:] In a dual trace oscilloscope, the resistances R1 and R2 are used for adjusting the magnitudes of the amplitudes of the signals A and B of the two channels A and B.

4. What is the role of a square wave generator?
a) generates square waves
b) generates triangular waves
c) generates saw-tooth signals
d) generates alternate inputs

Answer: d [Reason:] A square wave generator in a dual trace oscilloscope provides alternate biasing signals to the switches Q3 and Q4.

5. How many switches work at a time?
a) 1
b) 3
c) 2
d) 5

Answer: a [Reason:] In a dual trace oscilloscope, the square wave generator provides alternate bias signals to the switches Q3 and Q4. When Q3 is conducting, Q4 remains off while Q3 is off, Q4 conducts.

6. Square wave generator doesn’t reproduce the signals on the screen.
a) True
b) False

Answer: b [Reason:] In a dual trace oscilloscope, the square wave generator reproduces two signals on the screen. When the switching frequency of the square wave generator is higher than that of the individual signals, the bits of each signal are provided alternately to the vertical inputs.

7. A multitrace oscilloscope makes use of __________
a) three traces
b) two traces
c) many traces
d) one trace

Answer: c [Reason:] In a multitrace oscilloscope, a signle electron beam is used. It makes use of several traces by switching the the Y deflection plates from one input signal to the other.

8. A dual beam oscilloscope has __________
a) 2 beams
b) 4 beams
c) 6 beams
d) 8 beams

Answer: a [Reason:] In a dual beam oscilloscope, the beams are deflected horizontally by means of a common set of plates. Each electron beam has its own set of vertical deflection plates.

9. Two voltages can be studied simultaneously by making use of __________
a) single electron gun
b) two electron guns
c) four electron guns
d) six electron guns

Answer: b [Reason:] On the Cathode Ray Oscilloscope, two voltages can be studied simultaneously by means of two electron guns generating two separate beams through a special cathode ray tube.

10. A dual beam oscilloscope has __________
a) 8 vertical deflection plates
b) 6 vertical deflection plates
c) 2 vertical deflection plates
d) 4 vertical deflection plates

Answer: c [Reason:] In a dual beam oscilloscope, there are two vertical deflection plates and two separate channels. Each channel consists of a preamplifier and an attenuator stage.

11. Sweep generator is triggered by __________
a) oscillator
b) flip-flop
c) transformer
d) channel A or B

Answer: d [Reason:] In a dual beam oscilloscope, the sweep generator is triggered internally by means of either the channel A signal or the channel B signal.

12. A sweep generator can be triggered by an external switch as well.
a) True
b) False

Answer: a [Reason:] In a dual beam oscilloscope, the sweep generator can be triggered by means of an external switch or a line frequency signal. This is done through means of a trigger selector switch.

13. A dual beam oscilloscope has same sweep rates for different channels.
a) True
b) False

Answer: b [Reason:] 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.

14. In a multi-beam oscilloscope __________
a) single beam is produced
b) three beams are produced
c) many beams are produced
d) two beams are produced

Answer: c [Reason:] In a multi-beam oscilloscope, several beams are produced from a single tube. Each system is made up of separate set of vertical deflection plates and a common time base system.

## Set 2

1. Induction type instruments are used for ____________
a) A.C. measurements
b) D.C. measurements
c) Resistance measurements
d) Voltage measurements

Answer: a [Reason:] A.C. measurements are made using Induction type instruments. Induction type energy meter is used to measure the energy that is consumed in A.C. circuits only.

2. Driving system in an induction type single phase energy meter consists of _________
a) one magnet
b) two electromagnets
c) five electromagnets
d) ten magnets

Answer: b [Reason:] In an induction type single phase energy meter, the driving system consists of two electromagnets, namely series electromagnet and shunt electromagnet.

3. Series electromagnet consists of _________
a) L shaped laminations
b) T shaped laminations
c) U shaped laminations
d) Y shaped laminations

Answer: c [Reason:] The driving system of an induction type single phase energy meter consists of U shaped laminations made of silicon steel. The laminations are insulated from one another and pressed to form the core.

4. Shunt magnet consists of _________
a) N shaped laminations
b) E shaped laminations
c) S shaped laminations
d) M shaped laminations

Answer: d [Reason:] The driving system of an induction type single phase energy meter consists of M shaped laminations made of silicon steel. The laminations are insulated from one another and pressed to form the core of the shunt magnet.

5. Shunt magnet has _________
a) large turns of wire
b) small turns of wire
c) medium turns of wire
d) no turns or wires

Answer: a [Reason:] The central limb of the shunt magnet has a large number of turns. It connected across the supply and is known as the voltage coil or potential coil. It is excited using a current value that is proportional to the applied voltage.

6. Moving system of the induction type single phase energy meter has _________
a) heavy aluminium disc
b) light aluminium disc
c) medium aluminium disc
d) no aluminium disc

Answer: b [Reason:] Aluminium disc is provided in the air gap between the series and shunt magnets. Jewel bearings support the spindle. Hence the moving system in a induction type single phase energy meter consists of light aluminium disc.

7. Braking system consists of _________
a) bar magnet
b) temporary magnet
c) permanent magnet
d) super magnet

Answer: c [Reason:] In an induction type single phase energy meter, edge of the aluminium disc consists of a permanent magnet also known as a brake magnet. E.m.f is induced in the aluminium disc when it rotates as a result of the magnetic field produced by the brake magnet.

8. What is the effect of eddy currents in the aluminium disc?
a) varies by a factor of twice the disc length
b) independent of the disc speed
c) varies by a factor of four times the disc size
d) proportional to the disc speed

Answer: d [Reason:] The eddy currents induced in an aluminium disc vary in proportion to the speed of the disc. As a result the braking torque exerted on the disc varies in proportion to the speed.

9. An energy meter produces a flux of ∅ when connected to a supply V.
a) True
b) False

Answer: a [Reason:] Flux ∅ is produced in an energy meter when it is connected to a supply voltage of magnitude V volts. Since the potential coil is highly inductive, current and flux lag the voltage by 90°.

## Set 3

1. What led to development of PC based transducers?
a) low cost
b) medium cost
c) high cost
d) zero cost

Answer: a [Reason:] Easy availability, low cost and large scale usage of Personal Computers have led to the development of interfaces between PC and the transducer outputs.

2. ADD ON card is used for _______
a) to reduce noise
b) communication
c) to boost the magnitude
d) to measure voltage

Answer: b [Reason:] PC based data acquisition system makes use of an ADD ON card for the purpose of communication and analysis of multiple measurement data.

3. PC based data acquisition system displays system parameters
a) once in a while
b) intermittently
c) continuously
d) only at specific intervals

Answer: c [Reason:] A PC based data acquisition system displays the parameters of a system in a continuous manner. As a result all the parameters are monitored instantaneously and conveniently.

4. What are MIMIC displays?
a) man-material interface
c) man-machine interface
d) man-machine interface

Answer: d [Reason:] In a PC based data acquisition system, MIMIC displays are used for displaying the data measured at any part of a system on the screen. MIMIC stands for man-machine interface.

5. System parameters are distinguished by physical attributes.
a) True
b) False

Answer: a [Reason:] In a PC based data acquisition system, physical attributes such as blink, underline, inverse video, etc are used to display the system parameters.

6. Personal computer does not contain additional hardware in a PC based data acquisition system.
a) True
b) False

Answer: b [Reason:] In a PC based data acquisition system, the personal computer consists of additional hardware for data analysis and data acquisition. These are integrated through the means of software.

7. Data analysis hardware is used for _______
a) making the process independent
b) slowing the process
c) fastening the process
d) making the process constant

Answer: c [Reason:] In a PC based data acquisition system, data analysis software is used for the purpose of mainly fastening the computations and analysis in case of DSP applications.

8. Input signal range in a PC based data acquisition system is _______
a) 0.10 mV to 1 V
b) 1 mV to 100 V
c) 5 mV to 5 V
d) 10 mV to 10 V

Answer: d [Reason:] In a PC based data acquisition system, the input signal in the range of 10 mV to 10 V is amplified by means of a digital programmable gain amplifier to a particular level.

9. Amplified input signal is digitised through ________
a) A/D converters
b) D/A converters
c) Rectifiers
d) Sigma delta modulators

Answer: a [Reason:] In a PC based data acquisition system, the amplified input signal is converted to digital form by making use of high speed A/D converters. These are interfaced to the PC bus.

## Set 4

1. How many types of acquisition methods are there in a digital storage oscilloscope?
a) 3
b) 6
c) 2
d) 4

Answer: a [Reason:] In a digital storage oscilloscope, there are three methods in which a digital signal can be captured and stored. They are as follows: Real time sampling Random repetitive sampling Sequential repetitive sampling.

2. An oscilloscope with 20 to 50 GHz needs a slow speed.
a) True
b) False

Answer: b [Reason:] 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.

3. In which method of acquisition, pretrigger event is lost?
a) Real time sampling
b) Random repetitive sampling
c) Sequential repetitive sampling
d) Analog Sampling

Answer: c [Reason:] 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.

4. In Sequential repetitive sampling how many samples are captured?
a) ten
b) five
c) two
d) one

Answer: [Reason:] 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>.

5. In Real time sampling, bandwidth is limited.
a) True
b) False

Answer: a [Reason:] 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.

6. Nyquist criteria states that
a) Fs = fmax/2
b) Fs ≥ 2fmax
c) Fs = fmax
d) Fs = 2

Answer: b [Reason:] 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.

7. What plays an important role in Real time sampling?
a) small memory and fast sampling
b) large memory and slow sampling
c) large memory and fast sampling
d) small memory and slow sampling

Answer: c [Reason:] 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.

8. A single trigger event can capture how many samples in Real time sampling?
a) 1
b) nm/2
c) 2nm
d) nm

Answer: d [Reason:] 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.

9. In Real time sampling what is the 3 dB bandwidth?
a) fs/4
b) fs/8
c) 2fs
d) fs

Answer: a [Reason:] In Real time sampling, the 3 dB bandwidth is set to fs/4 with an overshoot of 5%. Here fs is the sampling frequency.

## Set 5

1. Electronic voltmeters use electronic circuits.
a) True
b) False

Answer: a [Reason:] Voltmeters that make use of rectifiers, diodes, amplifiers, etc in order to produce a current that is in proportion to the quantity that is being measured is known as an electronic voltmeter.

2. In olden days voltmeters were __________
a) made of transistors
b) made of vaccum tubes
c) made of transformers
d) made of diodes

Answer: b [Reason:] Initially, voltmeters were made of vaccum tubes. These voltmeters were known as vaccum tube voltmeters (VTVM).

3. Modern day voltmeters are made of __________
a) made of transformers
b) made of vaccum tubes
c) made of transistors and diodes
d) made of insulated iron coils

Answer: c [Reason:] Nowadays in voltmeters, transistors and semiconductor diodes are used. A transistor voltmeter makes use of transistor in a voltmeter.

4. FETVM is __________
a) an ammeter
b) a galvanometer
c) a multimeter
d) a voltmeter

Answer: d [Reason:] Field effect transistors can also be used at the input. Such voltmeters are known as FETVM (Field Effect Voltmeter).

5. Electronic voltmeters are __________
a) compact
b) large in size
c) not portable
d) difficult to use

Answer: a [Reason:] When compared to conventional analog voltmeters, electronic voltmeters are compact and also portable. This is due to the small size of the components.

6. Electronic voltmeters are not accurate.
a) True
b) False

Answer: b [Reason:] Compared to analog voltmeters, electronic voltmeters are very accurate and precise.

7. Electronic voltmeters are __________
a) dependent of frequency
b) dependent of voltage
c) independent of frequency
d) dependent of current

Answer: c [Reason:] Usually electronic voltmeters can measure frequency in the range of a few volts D.C. to frequencies of the order of hundreds of MHz. As a result, the effect of frequency on the response of electronic voltmeters is negligible.

8. Dynamic range of electronic voltmeter is __________
a) zero
b) limited
c) narrow
d) wide

Answer: d [Reason:] When compared to conventional analog voltmeters, the dynamic range is very wide and improved in electronic voltmeters. Very low as well as very high input signals can be measured using an electronic voltmeter.

9. Loading effect in electronic voltmeters is __________
a) nil
b) high
c) low
d) medium

Answer: a [Reason:] In an electronic voltmeter as the power is supplied by an external circuit, there is no loading effect. In a PMMC instrument, a minimum current of 50 µA is obtained from the signal that is to be measured and this leads to loading effect.

10. Electronic voltmeters are ____________
a) measure high level signals
b) measure low level signals
c) measure medium level signals
d) don’t measure any signal