MPPGCL JE Electronics Mock Test - 4 - Electronics and Communication Engineering (ECE) MCQ

Concept:

For a compensated semiconductor with an acceptor concentration greater than the donor concentration, the majority carrier concentration is calculated as:

With Na - Nd ≫ ni, the above equation becomes:

n0 ≅ Nd - Na

The conductivity for compensated p-type material is given as:

σ_p = qμ_p[N_a - N_d]     ---(1)

μ_p = mobility of holes 

Current density in compensated p-type material is:

J = σpE     ---(2)

E = Electric Field

Calculation:

Given:

Na = 1016/cm3 

Nd = 5 × 1015/cm3

μ_p = 500 cm2/V-sec

E = 5 V

From equation (1) conductivity can be calculated:

σp = 1.6 × 10^-19 × 500 × [10 - 5] × 10¹⁵

σp = 0.4 Ω^-1cm^-1

Now the current density can be calculated from equation (2):

J = 0.4 × 5

J = 2 A/cm²

• A Programmable Logic Controller, or PLC for short, is simply a special computer device used for industrial control systems.
• They are used in many industries such as oil refineries, manufacturing lines, conveyor systems and so on. Where ever there is a need to control devices the PLC provides a flexible way to "softwire" the components together.
• PLCs come in many shapes and sizes.  They can be so small as to fit in your shirt pocket while more involved controls systems require large PLC racks. 
• I/O – The PLC’s CPU stores and processes program data, but input and output modules connect the PLC to the rest of the machine; these I/O modules are what provide information to the CPU and trigger specific results.
• I/O can be either analog or digital; input devices might include sensors, switches, and meters, while outputs might include relays, lights, valves, and drives. Users can mix and match a PLC’s I/O in order to get the right configuration for their application.

Option 1 and 4 are wrong because

• PLC does not replace microprocessor infact it is a part of PLC.
• It does not require extensive wiring by PLC.

Concept:

The relation between data polynomial (A(x)), generator polynomial (g(x)) and transmission code polynomial (T(x)) is given as:

T(x) = g(x) A(x)

Analysis:

Given:

Code word → 0110100

T(x) = 0 . x⁰ + 1.x¹ + 1.x² + 0.x³ + 1.x⁴ + 0.x⁵ + 0.x⁶ 

 ∴ T(x) → x + x² + x⁴

T(x) = g(x) A(x)

Data word → 0100

Man–machine control system is a system in which the functions of a human operator (or a group of operators) and a machine are integrated. A manual system consists of hand tools and other aids which are coupled by a human operator who controls the operation. Operators of such systems use their own physical energy as the power source. In given figure we can see Mans hand and foot are working as actuator. An actuator is a component of a machine that is responsible for moving and controlling a mechanism or system or an actuator is a device that uses a form of power to convert a control signal into mechanical motion. Through hand we are controlling the steering motion and through foot we are controlling accelerometer and brake system. Since in this system controlling action is performed by man so it is Man controlled system.

The correct answer is option 3.

Key Points

The frames must be held before they are used if the date of the frames arrives at the receiver side faster than they can be processed. The receiver, in most cases, does not have enough storage space, particularly if it is receiving data from multiple sources. Frames may be discarded or service may be denied as a result of this. To keep the receiver from being overloaded by the frames, we need to tell the sender to slow down. This can only be achieved by input from the receiver to the sender.

The protocol we'll talk about now is called Stop and Wait because the sender sends one frame, then waits for confirmation from the receiver before sensing the next frame. Although data frames still require unidirectional communication, axillary acknowledgement frames travel in the opposite direction.

∴ Hence the correct answer is Simplex stop and wait protocols.

Concept:

The carrier Bandwidth Requirement in PCM depends upon the type of pules used in representing binary ‘1’ and ‘0’.

• If sinc function is used to generate PCM, then

            ; where R_b = Bit rate, given by;

            R_b = n f_s.

• If rectangular pulse are used; Bandwidth is given by;

     B.W. = R_b = n f_s (f_s = sampling frequency)

Calculation:

Since we are asked to calculate the minimum Bandwidth, we’ll assume that sinc pulses are used, and the message is sampled at a minimum sampling rate which is the Nyquist rate only.

f_s = 2 × f_max; where f_max is the maximum frequency present at the méssage signal.

For the given signal, f_max= 2 kHz

f_s = 2 × f_max = 2 × 2 kHz

So, f_s = 4 kHz

Given, n = 6 bits.

Concept:

The common-emitter current gain (β) is the ratio of the transistor's collector current to the transistor's base current, i.e.

I_C = β I_B

Calculation:

Given:

I_B = 100 μA and β = 200

The collector current will be:

I_C = β I_B = 200 × 100 μ

I_C = 20 mA

Important Point

The common base DC current gain (α) is a ratio of the transistor's collector current to the transistor's emitter current, i.e.

The transistor currents are related by the relation:

I_E = I_B + I_C

α can now be written as:

Dividing both the numerator and denominator by I_B, we get:

Since 

 'or'

Concept:

Mutual Inductance

When two coils are placed close to each other, a change in current in the first coil produces a change in magnetic flux, which lines not only the coil itself but also the second coil as well. The change in the flux induced voltage in the second coil. The voltage is called induced voltage and the two coils are said to have a mutual inductance.

The coupling coefficient K represents how closely they are coupled.

We have expression 

Where 

M = Mutual inductance

L1 = Inductance of coil one

L2 = Inductance of coil two

Calculation:

Given

L1 = 16 mH

L2 = 25 mH

K = 1

For the maximum value of inductance, the value of K must be equal to 1

h parameter equations:

V₁ = h₁₁I₁ + h₁₂V₂

I₂ = h₂₁I₁ + h₂₂V₂

From the above equations, it is clear that Hybrid parameters express V₁ and I₂ in terms of I₁ and V₂.

These parameters are known as Hybrid because they use Z parameters, Y parameters, voltage ratio and current ratio, to represent the relationship between voltage and current in a two-port network.

Concept:

A general expression of an FM signal is given by:

The instantaneous frequency will be:

The deviation from the carrier frequency will be:

δ = m(t) K_f

m(t) = Modulating signal

K_f = Frequency sensitivity of the FM modulator.

Note: We observe that the frequency deviation is independent of the frequency of the modulating signal.

Important Point

Modulation Index (β) in FM is given by:

k_f = frequency sensitivity

A_m = modulating voltage

The full scale output voltage of the given step size  is:                             

V_fs= where n is the number of bits

Now ,for question n = 8 and  = 20 mV

V_fs=

V_fs = 5.1 V

0024 H is the restart address of TRAP interrupt in 8085 microprocessor.

Key Points

The priority of interrupts in the decreasing order:

TRAP > RST 7.5 > RST 6.5 > RST 5.5

Hence, The highest priority interrupt in 8085 is TRAP

Important Point 

The impulse response and frequency response are two attributes that are useful for characterizing the linear Time invariant (LTI) system.

A continuous-time LTI system is usually shown as:

y(t) = x(t) * h(t)

* - represents the convolution

• LTI system theory is also used in ‘image processing’ and “field theory”, where the LTI system has spatial dimensions instead of or in addition to the temporal dimension.
• The fundamental result in LTI system theory is that only the LTI system can be characterized entirely by a single function called the system’s “impulse response”.
• LTI systems can also be characterized in the frequency domain by the system’s transfer function which is the Laplace transform for continuous & z-transform in the case of a discrete system.
• For all LTI systems, the eigenfunction and the basis functions of the transforms, are “complex exponentials”.

Concept:

The built-in potential barrier for a PN junction with given doping concentration N_a, N_d, is given by:-

Calculation:

Given, N_a = 10¹⁸/cm³

N_d = 10¹⁸/cm³

n_i = 1.5 × 10¹⁰/cm³

kT/q = 25 mV

So,

Sampling is the process of recording the values of a signal at given points in time. For A/D converters, these points in time are equidistant. The number of samples taken during one second is called the sample rate.

The Sampling Theorem states that a signal can be exactly reproduced if it is sampled at a frequency F, where F is greater than twice the maximum frequency in the signal.

The sampling rate for an analog signal must be at least two times as high as the highest frequency in the analog signal in order to avoid aliasing.

Conversely, for a fixed sampling rate, the highest frequency in the analog signal can be no higher than a half of the sampling rate.

Any part of the signal or noise that is higher than a half of the sampling rate will cause aliasing.

In order to avoid this problem, the analog signal is usually filtered by a low pass filter prior to being sampled, and this filter is called an anti-aliasing filter.

Sometimes the reconstruction filter after a digital-to-analog converter is also called an anti-aliasing filter.

The correct answer is option 1.

Concept:

Mobile Communication:

Mobile Communication defines a framework for the operation of mobile computing technology. In this context, mobile communication refers to an infrastructure that allows wireless devices to communicate with one another in a seamless and reliable manner.

Mobile computing is a technology that allows users to send data from one device to another without the use of a physical link or cables.

There are two basic types of mobile communication systems are,

1. Infrastructured Mobile Communication:

• Relies on network infrastructure laid out by service providers.
  • Example: Cellular Communication
    • Uses Base Trans-receiver System (BTS) with two types of antennas:
      • Vertical Antenna (RF/GSM Antenna): Operates in MHz range, handles signal transmission/reception.
      • Drum Antenna (Microwave Antenna): Operates in GHz range, creates links between BTS.

2. Infrastructure-less Mobile Communication:

• Eliminates the need for pre-installed infrastructure, making communication cost-effective and independent of BTS.
• Categories include:
  • Mobile Adhoc Network (MANET): Temporary networks established as needed; used in military, various research fields.
    • Subtypes of MANET:
      • FANET (Flying Adhoc Network): Connects UAVs for enhanced capability.
      • VANET (Vehicular Adhoc Network): Enables inter-vehicular communication, assists in traffic monitoring and safety.
      • SANET (Smartphone Adhoc Network): Uses smartphones' adhoc networking for communication without BTS.
  • Wireless Sensor Network (WSN): Uses sensors to collect and transmit data to remote servers, used in environmental monitoring, pollutant tracking, and target tracking.

Hence the correct answer is 2.

PLC and SCADA:

• The primary difference between a PLC (Programmable Logic Controller) and SCADA (Supervisory Control and Data Acquisition) is that a PLC is hardware and SCADA is software.
• PLCs are designed to control complex industrial processes, such as controlling electrical machines.
• They are simple to program and fully scalable to an operation’s requirements.
• They’re also used to collect data from the systems they control.
• SCADA is a central system used to monitor and run the processes.
• SCADA is typically software installed on a computer, and one of its major functions is to act as an interface with industrial machines (or Human-Machine Interface, or HMI).
• SCADA systems are often used in conjunction with PLCs and other devices.
• Data from PLCs and Remote Terminal Units (RTUs) are relayed to the system, and commands are entered into the HMI to make adjustments to the processes they control.

The correct answer is option 2):(2 A and 0 V)

Concept:

The resistance of the ideal ammeter is zero

When two resistors are connected in series the total resistance will be the sum of individual resistors

The current I =

Calculation:

Given

R =  2+ 3 = 5

I = 

= 10/5 = 2A

The voltmeter is connected across the ammeter so there is a voltage drop in the ammeter because The resistance of the ideal ammeter is zero

Voltmeter reads zero.

In the circuit shown below, the reading of the ideal ammeter and voltmeter, respectively, will be 2 A and 0 V.

PRF Doppler has a range of ambiguities.

Important Points

1. Pulse DOPPLER RADAR:

• A pulse-Doppler radar is a radar system that determines the range to a target using pulse-timing techniques and uses the Doppler effect of the returned signal to determine the target object's velocity.
• A pulse-Doppler radar can be ambiguous in either range or Doppler frequency.
• The ambiguity of a radar depends on the selected pulse repetition frequency (PRF).
• Three modes of airborne radar operation are well known: the high PRF (HPRF), medium PRF (MPRF), and low PRF (LPRF) mode.
• A good choice of PRF to achieve a large unambiguous range will be a poor choice to achieve a large unambiguous velocity and vice versa, this is known as the concept of the Doppler dilemma.
• So in the case of high PRF pulse radar has no ambiguity in Doppler frequency but ambiguities in range.

2. MTI RADAR:  

• Moving Target Indicator Radar (MTI) is used for detecting the movable target.
• It receives only the echo signal due to that movable target for this purpose it uses the principle of the Doppler Effect.
• According to the Doppler effect, the frequency of the received signal will increase if the target is moving towards the direction of the Radar.
• Similarly, the frequency of the received signal will decrease if the target is moving away from the Radar. Due to receiving moving target echoes, MTI radar has many Doppler ambiguities, it can’t neglect stationary objects echoes.

The correct answer is Cache.

Key Points

• A/An cache is a special high-speed storage mechanism used in computers.
• A cache is a hardware or software component that stores data so that future requests for that data can be served faster.
• With Internet browsers, the cache is a temporary storage area where website data is stored.
• Cache memory has the shortest access time.
• The processor can retrieve data or instructions from the cache memory.
• Cache memory acts between CPU and RAM.

For making an LED a Direct band gap (DBG) semiconductor is used.

The band gap is called "direct" if the momentum of electrons and holes is the same in both the conduction band and the valence band; an electron can directly emit a photon.

In an "indirect" gap, a photon cannot be emitted because the electron must pass through an intermediate state and transfer momentum to the crystal lattice.

In other words we can say that a DBG semiconductor is one in which the maximum energy level of the valence band aligns with the minimum energy level of the conduction band with respect to momentum as shown in the figure.

In case of a Indirect Band gap (IBG) semiconductor, due to a relative difference in the momentum, first, the momentum is conserved by release of energy and only after the both the momenta align themselves, a recombination occurs accompanied with the release of energy, see in the  figure.

The probability of a radiative recombination, hence, in case of IBG semiconductor is much less in comparison to that in case of DBG semiconductors.

Hence, the efficiency factor of a DBG semiconductor is much more than that of a IBG semiconductor.

The efficiency factor of a DBG semiconductor is much more than that of a IBG semiconductor.

That is the reason why DBG semiconductors are always preferred over IBG for making optical sources such as LED. 

Some examples of IBG are GaA_S or alloys of Group III and Group IV elements.

Since GaAsP is a direct band gap material that’s why it is most preferred material for fabrication of LED. 

The minimum change in the measured variable which produces an effective response of the instrument is known as resolution.

Concept:

The static performance parameters of the instruments are:

1. Accuracy
2. Precision
3. Resolution
4. Threshold
5. Static sensitivity
6. Linearity
7. Hysteresis
8. Backlash
9. Dead band
10. Drift

• Accuracy: It is the closeness with which an instrument reading approaches the true value of the quantity being measured. It means conformity to truth.
• Precision: It is defined as the ability of the instrument to reproduce a certain set of readings within a given accuracy
• Drift: It is defined as the variation of output for a given input caused due to change in the sensitivity of the instrument to certain interfering input like temperature changes, component instability, etc.
• Resolution: It is defined as the smallest increment in the measured value that can be detected with certainty by the instrument.
• Threshold: It is defined as the minimum value of input below which no output can be detected.
• Static sensitivity: It is defined as the ratio of the magnitude of response to the magnitude of the quantity being measured.
• Linearity: It represents the output of the instrument which is a linear function of the input.
• Hysteresis: It is defined as the magnitude of error caused in the output for a given value of input when this value is approached from opposite directions, i.e. from ascending order and then descending order.
• Dead band: It is defined as the largest change of the measurand to which the instrument does not respond.
• Backlash: It is defined as the maximum distance or angle through which any part of the mechanical system may be moved in one direction without causing motion of the next part.

Given, LCM = 225, HCF = 5,
First Number = 25 , Second Number = ?
We can find the Second Number with the help of given formula,
"LCM × HCF = 1st Number× 2nd Number"
⇒ 225 × 5 = 25 × 2nd Number

∴ 2nd Number = 45

The side of the square must be the same as the breadth of the rectangle.
Side of the square = 4 meters
So the answer = 4 × 4 = 16 m²
Hence, Option D is correct.

The correct answer is the Sardar Hukum Singh committee.

• Haryana became the 17th state of India in 1966 on the recommendation of the Sardar Hukum Singh committee.

Key Points

• After the independence of India in 1947, Haryana remained part of Punjab.
• But Hindus and Sikhs both demanded separate states.
• This movement gained momentum after 1955 and had its full intensity in 1960.
• Haryana was separated from Punjab in 1966 with the passage of the Punjab reorganization act and on the recommendation of the Sardar Hukum Singh parliamentary committee.
• This committee was formed in 1965.

Checking → statement I:

References:

P is married to U.

V is married to R.

Q is the husband of W.

S is the daughter-in-law of W.

Inferences:

From the above references, we can conclude the following:

So, we can’t conclude the relation between X and S.

Thus, statement I alone is not sufficient to answer the question.

Checking → statement II

References:

V is the father of Q.

U is the mother-in-law of Q.

T is the sibling of X.

T is unmarried.

Inferences:

From the above reference, we can conclude the following:

So, we can’t conclude the relation between X and S.

Thus, statement II alone is not sufficient to answer the question.

Checking → statement I and II:

References:

P is married to U.

V is married to R.

Q is the husband of W.

S is the daughter-in-law of W.

V is the father of Q.

U is the mother-in-law of Q.

T is the sibling of X.

T is unmarried.

Inferences:

From the above references, we can conclude the following:

So, we can conclude that X is the husband of S.

Thus, statement I and II together is sufficient to answer the question.

Hence, option D is correct.

Since the train travels at 60 kmph, it’s speed per minute is 1 km per minute. Hence, if it’s speed
with stoppages is 40 kmph, it will travel 40 minutes per hour.

The logic follows here : 
1. Sukhoi Su-30MKI is a Fighter Jet.
2. INS Vikrant is different from these two, it is an Aircraft Carrier.

The least possible Venn diagram for the given set of words is :

Hence, the correct answer is "Option (4)".

Additional Information

INS VIKRANT

• INS Vikrant is a 37,500-tonne carrier and has been launched almost four-and-a-half years after its keel was laid.
• The launch of warship, which has a length of 260 metres and is 60 metres wide.
• The launch has marked India's entry into a select club of countries capable of designing and building a carrier of this size and capability.
• There are 14 decks in all, including five in the superstructure. The ship has over 2,300 compartments, designed for a crew of around 1,700 people, including specialized cabins to accommodate women officers.
• There are 14 decks in all, including five in the superstructure. The ship has over 2,300 compartments, designed for a crew of around 1,700 people, including specialized cabins to accommodate women officers.

Sukhoi Su-30MKI

• The Sukhoi Su-30MKI is a twinjet multirole air superiority fighter developed by Russia's Sukhoi and built under license by India's Hindustan Aeronautics Limited (HAL) for the Indian Air Force (IAF). A variant of the Sukhoi Su-30, it is a heavy, all-weather, long-range fighter.
• The IAF has nearly 260 Su-30MKIs in inventory as of January 2020.
• Based on the Su-30 fighter aircraft, Su-30MKI is equipped with thrust vectoring control and canards.
• The aircraft has a length of 21.9m, wingspan of 14.7m and a height of 6.4m.
• The maximum take-off weight of Su-30MKI is 38,800kg.
• The Su-30MKI is also equipped with a N011M passive electronically scanned array radar, OLS-30 laser-optical locator system and Litening target designation pod to guide air-to-surface missile and laser guided munitions.
• The Su-30MKI is armed with a 30mm Gsh-30-1 cannon with 150 rounds of ammunition.
• The Su-30MKI fleet of IAF was fitted with air-launched version of BrahMos supersonic cruise missiles and was successfully tested in November 2017.
• The BrahMos can strike targets within the range of 290km.
• The IAF completed the successful integration of the cruise missile on the fighter, with the third live firing of the missile from the aircraft in December 2019.

Original number - 7 6 5 3 4 2 1 8

Hence, required digit = 6