Basic Electronics Engineering Test Questions Set 9

ANSWER: All of the above

Explanation:
No explanation is available for this question!

ANSWER: All of the above

Explanation:
No explanation is available for this question!

ANSWER: Adjusted Output from signal amplifier is directly proportional to the measured quantity

Explanation:
No explanation is available for this question!

ANSWER: Output Module

Explanation:
No explanation is available for this question!

ANSWER: Timer Call of MFC Library

Explanation:
No explanation is available for this question!

ANSWER: Interfacing Circuit

Explanation:
No explanation is available for this question!

ANSWER: Power Supply Unit

Explanation:
No explanation is available for this question!

ANSWER: System Bus

Explanation:
No explanation is available for this question!

ANSWER: Proximity Switches

Explanation:
No explanation is available for this question!

ANSWER: All of the above

Explanation:
No explanation is available for this question!

ANSWER: For DC level shifting

Explanation:
Level shifter or translator is usually connected in a typical Op-Amp so as to shift the DC Level at the output of intermediate stage which is grounded onward to zero. Intermediate stage is basically a differential amplifier which is driven by the previous state output. The DC Level at the output of intermediate stage is good above ground potential in case of direct coupling. Hence, it is obligatory to use the level shifter in OP-Amps.

ANSWER: Infinite output offset voltage when input voltage is zero

Explanation:
An ideal Op-Amp has an infinite CMRR, Slew Rate & Bandwidth. But, the output voltage is absolutely zero when the input voltage is zero. All the mentioned parameters tend to infinity except output voltage & resistance so that it becomes feasible for an output to drive infinite number of other devices.

ANSWER: A & C

Explanation:
Non-inverting amplifier has greater output voltage than that of its input voltage & is in phase with it. On the contrary, the output voltage of inverting Op-amp goes out of phase in correspondence to input signal by an angle of 180° or in terms of opposite polarity. In case of non-inverting amplifier, the input is applied to non-inverting input terminal & inverting terminal is set to be grounded while in case of inverting amplifier, the input is applied to inverting terminal & non-inverting terminal is at ground level. Therefore, due to the configurational assortments in inverting & non-inverting amplifier, the output voltage & phase level (in or out) also exhibit variations.

ANSWER: Wheatstone Bridge

Explanation:
Structural Configuration of a differential amplifier is semantic to wheatstone bridge since the amplification is done between two input signals in exactly similar way just like the outputs of Wheatstone bridge network. The cardinality of differential amplifier can be most probably seen in industrial & instrumentation aspects due to superior ability of rejecting common mode noise voltages.

ANSWER: Both a & b

Explanation:
Open loop configuration of Op-amp may increase the threat of distortion as well as clipping of output signal. Due to this reason, the output gets switched between the positive and negative saturation levels. Hence, this is the major drawback because of which it is highly impossible to use Op-amps with open loop configurations in linear circuit applications.

ANSWER: All of the above

Explanation:
The thermal drift phenomenon of voltage & current are taken into consideration in accordance to the values of input offset voltage, input bias current & input offset current. However, variations in these parameters ultimately changes the level of thermal drift (Drift voltage & Drift current).

ANSWER: Offset minimizing resistors

Explanation:
Offset minimizing resistors are the only means of reducing the amount of output offset voltage. Voltage Controllers & capacitors are not meant for controlling the amount of offset output voltage in Op-amps.

ANSWER: Scaling Amplifier

Explanation:
Inverting amplifiers are generally categorized in the form of summing amplifier, Scaling amplifier and averaging amplifier. Basically, each input voltage gets amplified by a different factor & then weighted differently at the output level. Hence, this scaling amplifier is also referred as 'Weighted Amplifier'. This can only be possible when all input resistances belong to the different values. On the controversial aspect, summing amplifier generates the output voltage which is equal to negative summation of all inputs times the circuit gain. Apart from this, average circuit produces the output voltage by considering the average of all input voltages. Only the scaling or (weighted amplifiers) possesses this characteristic of operation that exhibits different weightages at the output.

ANSWER: Low-level Output Signal

Explanation:
The leading role of an instrumentation amplifier signifies is the amplification & magnification of low level signals in order to drive the display or an indicator. High level signal does not need to get amplify & therefore, instrumentation amplifiers are targeted to amplify low level signals semantically where there is necessity of low noise, low thermal & time drifts, high input resistance & precise closed-loop gain. Besides these, instrumentation amplifiers like μ A725, ICL 7605 & LH0036 find their wide range of applications due to dexterity in precision & stability at the most confined level.

ANSWER: Unit change in R per unit change in 'l'

Explanation:
Sensitivity is basically a dimensionless quantity & implies the change in resistance due to change in length of wire at a unity level. Generally, there are mainly two types of strain gauges like wired strain gauge & semiconductor strain gauge. Semiconductor strain gauges are sensitive to maximum extent as compared to that of wire type & hence they yield more accuracy and resolution. Intuitively, sensitivity measures the degree of accuracy & resolution. More the level of sensitivity, high will be the rate of accuracy & resolution.

ANSWER: Temperature Controller

Explanation:
Temperature control circuit can be built up by using a thermistor in bridge circuit along with the replacement of a meter by a relay in the structural configuration of differential instrumentation amplifier. It is possible to control the current in the heat-generating circuit with an assistance of relay driven by the temperature controller itself. Temperature indicator is also constructed using thermistor as a transducer with the only difference that output meter is calibrated in degree Celsius or Fahrenheit. Despite bridge circuits, light-intensity meter can be built-up by using a photocell as a transducer while two thermistors are adjacently connected in thermal conductivity meter circuits.

ANSWER: 100 ohm

Explanation:
Photo-conductive cells can be categorized under the family of photo-detectors which shows variation in the resistance due to incidence of light or any other form of radiant energy. The resistance value decreases with an increase in the intensity of incident light & hence the typical value of resistance of photo-conductive cells is absolutely 100 ohm. Materials like cadmium sulphide and silicon are used for photo conductive cells to greater extent since their conductivity is a function of incident radiant energy. Resistances of photo-conductive cell are noted along with the corresponding light intensities & then the resistances are expressed in terms of ohm while the light intensities are expressed in terms of meter candles (lux).

ANSWER: A & C

Explanation:
Integrator is basically a circuit where the output voltage forms an integral part of input voltage. If the feedback resistor gets replaced by a capacitor in a basic inverting amplifier, then the integrator circuit can be produced. If an input is in the form of a sinusoidal waveform then the output will generate a cosine waveform due to direct relationship of output voltage and negative negative integral of input voltage. Even, phase constant is not involved in case of differentiator & integrator. However, only the case of A & C is application from the integrator point of view.

ANSWER: Frequency Scaling

Explanation:
Frequency Scaling is a process of conversion of original cut-off frequency to a new cut-off frequency. Here, the frequency gets converted & not deviated or translated or divided before the conversion process. Frequency Scaling is most oftenly performed whenever there is a necessity to change the cut-off frequencies in filter designing process. Multiplication of either 'R' or 'C' by the ratio of original cut-off frequency to the new cut-off frequency gives a notion for changing the high cut-off frequency.

ANSWER: Less than 10

Explanation:
Narrow & Wide band-pass filters can be distinguished only on the basis of quality factor. This figure of merit conveys that if 'Q' > 10, the filter is considered to be a narrow band-pass filter whereas if 'Q' < 10, then the filter is considered as a narrow band-pass filter. Therefore, quality factor is a measure of selectivity which infers that the selectivity of the filter depends on the value of 'Q'. Higher the value of quality factor, more is the selectivity of the filter.

ANSWER: Narrow band reject filter

Explanation:
Band-reject filters are those which shows the frequency attenuation in the stop-band while they get passed outside this band. Similar to band-pass filters, band-reject filters also gets classified into wide & narrow band-reject filters. Narrow band-reject filter is commonly known as notch filter since it has high quality factor (Q>10) & bandwidth is very much smaller as compared to that of wide band-reject filters.
These narrow band-reject filters are widely used for single frequency rejection like 60 Hz power line frequency hum. For an instance, twin-T network. Notch filter finds its applications in the aspects of communication & biomedical instruments so as to remove the unwanted frequencies.

ANSWER: All-pass Filter

Explanation:
All-pass filters allows to pass all the frequency components of input signal without any attenuation by anticipating phase shifts for different frequencies. When signals undergo transmission by telephone wires, there is a definite change in phase. Thus, all pass filters are the means for compensating these phase changes, because of which they are generally termed as “Phase-Correctors” or “Delay Equalizers”. Output of Delay Equalizers can be generated by using Super-position theorem.

ANSWER: A2, B3, C1

Explanation:
The type of waveform generation by an oscillator totally depends on components used in the circuit. Hence, they can be sinusoidal if RC components are used while they can be square if LC components are used & even they can be saw-tooth or triangular if crystal oscillator is used. Crystal Oscillators are stable to maximum extent as compared to that of RC & LC oscillators due to higher figure of merit (Q). However, crystal & LC oscillators find their applications in generation of high frequency signals while RC oscillators are intended for audio-frequency applications.

ANSWER: Clamp Diodes

Explanation:
Comparator is a circuit which performs comparison between the signal voltage on one input of Op-amp with reference voltage on another input. The arrangement of diodes in comparator circuit is in such a way that they play a cardinal role in protecting Op-amp from getting damage due to excess of input voltage. These diodes intentionally undergoes clamping of difference input voltage to 0.7 or -0.7 volts. However, these diodes are also called as 'Clamp Diodes'.

ANSWER: Voltage Controlled Oscillator

Explanation:
Generally, the time constant helps in determining the frequency of oscillation in any oscillator. But, in some of the applications like Frequency Modulation (FM), Frequency Shift Keying (FSK) where the frequency needs to be controlled by input voltage. This input voltage performs the functionality of controlling voltage level & hence, precisely referred as 'Control Voltage'. This entire functionality is undertaken by Voltage -Controlled Oscillator (VCO). Another name of VCO is Voltage to frequency converter.
For e.g. Signetics NE/SE 566 VCO generates the triangular as well as square wave outputs simultaneously as a function of an input voltage. VCO are applicable in conversion of low-frequency signals into audio frequency ranges especially in bio-medical applications EEG (electroencephalograms) & ECG (electrocardiograms).

ANSWER: Both a & b

Explanation:
The comparator can be configured to be useful in the form of Zero-Crossing Detector by just adjusting reference voltage to zero. There is sometimes possibility that low frequency signal may consume some more time to cross zero volt because of which output voltage cannot switch over instantaneously from one saturation region to another. Also, the noise at the op-amp input terminals may fluctuate the output between positive & negative (+Vsat & -Vsat) saturation voltages. Hence, both the shortcomings can be resolved by using positive or (regenerative) feedback.

ANSWER: Positive Feedback Comparator

Explanation:
Hysteresis phenomenon is a dead-band condition where the output switches from +Vsat to -Vsat whenever input value becomes greater than the upper threshold voltage. Thus, when the input value falls below lower threshold voltage, then the output gets returned to its original position or state +Vsat. Therefore, hysteresis can be evaluated as a difference of upper threshold voltage (V_ut) and lower threshold voltage (V_lt.). The most probabilistic approach of hysteresis occurrence can be observed in the comparators with positive (or regenerative) feedback. The significant advantage of hysteresis is that it increases the speed of operation of the comparator.

ANSWER: Response Time

Explanation:
Typical electrical parameters of comparator include positive & negative output levels, strobe current & strobe release time, response time & saturation voltage. Thus, the interval between input step function & the duration of crossing logic threshold voltage at the output gives the conceptual idea of response time. On the other hand, the time required for rising the logic threshold voltage at the output after the driving session of strobe terminal is conducted from zero to one logic level. Eventually, the parameter of settling time is totally not involved in comparators.

ANSWER: Microprocessor Interfacing

Explanation:
Microprocessor interfacing is an application of ADCs while all the remaining applications like microcomputer interfacing, programmable power supply & CRT graphics are the applications concerned to digital to analog converters in accordance to their functionalities.

ANSWER: Resolution & Settling time

Explanation:
By taking into consideration the approach of application point of view, selection of an efficient digital to analog converters must have good specifications in terms of resolution, linearity or non-linearity of error, Gain & offset errors along with the settling time. Resolution specifies the number of input bits with the valuation in the form of least significant bit (LSB) whereas the settling time implies the requirement of time for DAC output to settle down between positive or negative ½ LSB of the final value of digital input (which is generally zero to full scale). However, response & conversion time are not the valid specifications for DAC selection since they are of significant importance in ADC.

ANSWER: Reference voltage must be less than input voltage

Explanation:
Generation of clipping circuit using op-amp & rectifier diode is possible where the op-amp act as a voltage follower with diode in a feedback path. Since clipping circuit eliminates the positive parts of input signal, so the the value of reference voltage helps in determining the clipping level. Therefore, the voltage difference 'V_ref' must be smaller than input voltage. When V_in V_ref, then reference voltage is higher at the negative input as compared to that of the positive input.

ANSWER: IC 741

Explanation:
Op-amp ICs varying in the version of 741 are highly approved or sanctioned for military grade since the temperature range lies within -55° to 125°C. So, as the temperature level range display variations, the op-amp IC741 are further sub-categorized under the series of 741C, 741A & 741E & so on. Besides these, 741S & 741SC are recommended for military as well as commercial aspects due to high slew rate. Other ICs mentioned in the question are only applicable to certain specific sort of applications other than the military ones. Apart from these versions, IC 555 are widely applicable in timers, oscillators & pulse generators. IC LF 398 forms a leading part of sample & hold circuit while IC LM117 can be used as a switching regulator & also provides full overload protection to other ICs.

ANSWER: μ A741

Explanation:
The inceptional phase of first generation was initiated with the utility of IC op-amp 709. Several drawbacks related to performance characteristics were highlighted like no protection to short circuits, latch-up problem and absence of external frequency-compensating network for stable operation. All these major shortcomings were tackled by an internally compensated op-amp IC741 which had a provision of short-circuit protection, absence of latch-up problem & highly stable & proficient at the operational level. Hence, it is also regarded as 'Second-generation Op-amp'.

ANSWER: All of the above

Explanation:
Silicon steel EI butt stack method shows better permeability & high flux density along with the simplicity in construction phase. So, it is wide used in low-voltage switching regulators. Ferrite EI, U & toroid cores exhibits lower performance in the aspects of permeability, high temperature & expensive to greater extent. Powdered permalloy toroids possess are highly permeable with lower values of leakage inductance & losses. Due to this, they offer maximum stability & predictability but are very expensive similar to that of ferrite EI, U & toroid cores. However, all these mechanisms are adopted as per the requirement of desired application of switching regulator.

ANSWER: A2, B4, C1, D3

Explanation:
Corresponding to the manufacturers own productivity of ICs, they also go for the production of one another's renowned ICs. Thus, manufacturers generally holds the original type number in their own IC designation. For an instance, Op-amp 741 is originally developed by Fairchild but it also gets manufactured by different number of manufacturers under the category of their own designations. The pairs mentioned in the question clarifies this conceptual notion in the form of an illustration where the manufactures & their associated IC designations are mentioned.