MPPGCL JE Electronics Mock Test - 9 - Electronics and Communication Engineering (ECE) MCQ

The correct answer is option 4.

Pure AC resistive circuit

For a purely AC resistive circuit, the voltage and current are in the same phase.

Hence, the power factor (cosϕ) is unity.

The power in an AC circuit is given by:

P = VI cosϕ = positive value

For pure resistive load, cosϕ=0

Hence, P = VI = Power in the DC circuit

Therefore, the expression for power is the same as the DC circuit.

The effective of a data communications system depends on four fundamental characteristics:

Delivery, Accuracy, Timeliness and Jitter.

Delivery: The system must deliver data to the correct destination; Data must be received by the intended device or user

Accuracy: The system must deliver the data accurately; Data that have been altered in transmission and left uncorrected are unusable

Timeliness: The system must deliver data in a timely manner; Data delivered late are useless

The probability that an electron occupies an energy level E is given by the Fermi-Dirac probability function and It can be expressed by:

The probability that the energy level is not filled with an electron, i.e. empty =1 - f (E)

An energy state being empty is equivalent to the presence of a hole, i.e. positively charged particle.

Important Point

• At absolute zero, fermions will fill up all available energy states below a level EF called the Fermi energy with one (and only one) particle; They are constrained by the Pauli exclusion principle
• At higher temperatures, some are elevated to levels above the Fermi level
• For low temperatures, those energy states below the Fermi energy EF have a probability of essentially 1, and those the Fermi energy essentially zero

The output of FM modulator is of form

After passing the modulating signal through the differentiator we give as the input to the frequency modulator, i.e.

The expression of the output signal will be:

The differentiation of the integral will simply give the original signal.

We get a phase modulated signal which is of the form:

Concept:

The gain of non inverting amplifier : A_V = 1 + (R₂ / R₁)

Calculation:

From the given circuit diagram , the potentiometer can be varied in between 0 Ω to 10 KΩ.

R₂ = 200 KΩ ,  R₁ = ( 10 + R)

Gain :  A_V = 1 + (R₂ / R₁) = 1 + (200/10 + R)

For , R = 0 Ω ; 

A_V = 1 + (200 / 10) = 21

V_o = A_V × 0.5 = 21 × 0.5 = 10.5 V

For , R = 10 KΩ

A_V = 1 + (200 / 10 + 10) = 11

V_o = AV × 0.5 = 11 × 0.5 = 5.5 V

Additional Information
A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider.

As you turn the knob of a potentiometer, the resistance will vary.

Programmable logic array (PLA):

It is a kind of PLD (Programmable logic device) used to implement a combinational logic circuit.

1.It has a set of programmable AND gate planes which link a set of programmable OR gate planes.

Hence option (2) is the correct answer.

2.It has 2^N AND Gate for N-input variable and form or Gates it has m output.

PLA Design:

The memory IC used in a digital system is selected or enabled only for the range of address assigned to it and this process is called memory decoding.

It denotes the memory to be selected for a specific address.

Important Points

PLD’s (Programmable Logic Devices) are the circuits that contain an array of AND gates and another array of OR gates. There are three kinds of PLD’s depending upon the type of array, i.e.

• Programmable Read-Only Memory
• Programmable Array Logic
• Programmable Logic Array (PLA)
• ROM is a memory device that stores the binary information permanently.

PROM:

• It is known as programmable read-only memory
• It includes both AND array & OR array

Out of these two arrays AND array is fixed and OR array is programmable.

​​PAL: 

​Programmable AND array followed by fixed OR array

The correct answer is option 2): 6

Concept:

The range of the Galvanometer is extended by keeping a shunt resistance.

Here

R_m = internal resistance of the coil

R_sh = Shunt resistance

R_m and R_sh are in parallel, the voltage drop across the resistance is equal.

m is the multiplying factor

Calculation:

Given

R_m =  100 Ω 

R_sh = 20 Ω 

20 = 

m - 1 = 5

m = 6 

Concept:

The Y parameter equations are as follows:

I₁ = Y₁₁V₁ + Y₁₂V₂

I₂ = Y₂₁V₁ + Y₂₂V₂

Calculation:

Given, I1 = 4I2  & V2 = 0.25 I₂

When port 1 of two-port circuit is short-circuited, then V₁ = 0 V

I1 = Y12V₂

Y12 = 16

I2 = Y22V₂

Y22 = 4

In DPSK, the input to the balance modulator is given as:

b(t) = d(t) ⊕ b(t – T_b)

This represents the Ex-OR operation,

Now, sampled version of d(t) is the input m(n)

∴ The sampled version of b(t) is written as:

b(n) = m(n) ⊕ b(n – 1)

m(n) = { 1, 0, 1, 1, 0, 1 ….}

Considering initial storage element = 1

b(1) = m(1) ⊕ b(0)

= 1 ⊕ 1 = 0

b(2) = m(2) ⊕ b(1)

= 0 ⊕ 0 = 0

b(3) = m(3) ⊕ b(2)

= 1 ⊕ 0 = 1

b(n) = {0, 0, 1, 0, 0, 1, …}

The phase of the carrier = {π, π, 0, π, π, 0, …. }

PRF:

The pulse repetition frequency (PRF) is the number of pulses of a repeating signal in a specific time unit, normally measured in pulses per second.

In radar, a radio signal of a carrier frequency is turned on and off; the term "frequency" refers to the carrier, while the PRF refers to the number of switches.

Both are measured in terms of cycle per second, or hertz.

Concept:

Inductive impedance is given by:

jX_L = jωL

ω = frequency in radian/sec which can be written as:

ω = 2πf

f  = frequency in Hz

L = value of inductor in Henry

Similarly, the capacitive impedance is given by:

Calculation:

Given ω = 50 rad/sec

The capacitive reactance of the capacitor with C = 1000 μF will be:

The capacitance will, therefore be replaced with  -20j

Similarly, the inductor will be replaced with:

jωL = j × 50 × 500 mH

jωL = 25j

The resultant circuit will be, therefore:

Concept:

A function can be solved using K-map.

A four variable K-map has the following representation.

Observation:

f(A, B, C, D) = ∑(1, 3, 4, 6, 9, 11, 12, 14)

f = B D̅ + D B̅ 

So, Function f depends on only two variable and independent to other two variable.

Concept:

A transfer function is defined as the ratio of Laplace transform of the output to the Laplace transform of the input by assuming initial conditions are zero.

TF = L[output]/L[input]

For unit impulse input i.e. r(t) = δ(t)

⇒ R(s) = δ(s) = 1

Now transfer function = C(s)

Therefore, transfer function is also known as impulse response of the system.

Transfer function = L[IR]

IR = L^-1 [TF]

Calculation:

Given that r(t) = u(t), c(t) = t e^-t

Transfer function,

Concept:

A diode is in Forward bias if

V_D = V_P - V_N > 0.7 V

A diode is in Reverse bias if

V_D = V_P - V_N < 0.7

Analysis:

Assume both diodes in RB, or OFF or open circuited.

for diode D(a) → V_D = V_P - V_N = 10 V > 0.7 → FB

for diode D(b) → V_D = V_P - V_N = 0 V < 0.7 → RB

• The Fourier transform of a function is equal to its two-sided Laplace transform evaluated on the imaginary axis of the s-plane.
• The main drawback of Fourier transform (i.e. continuous F.T.) is that it can be defined only for stable systems, Whereas, Laplace Transform can be defined for both stable and unstable systems.
• An LTI system is stable if and only if the ROC of its system function H(s) includes the jω-axis [i.e., Re{s} = 0]  
• Fourier transform is defined only for stable signals. 
• From the given ROCs, B and C does not include the jω axis thus Fourier transform is not defined for B & C.

Leakage current:

• When the supply at the emitter-base junction is open-circuited, there is only reverse biasing in the base-collector junction.
• Therefore, this sets up a small amount of current called the leakage current.
•  It is highly temperature-dependent because it depends upon a number of minority charge carriers that are thermally generated and in turn depend upon temperature.
• The main source of the leakage current in a transistor is thermally generated minority carrier. consider common emitter configuration.

• When the switch is open, the emitter-base junction is an open circuit and so the value of input or base current is zero.
• But a leakage current I_CEO flows between collector and emitter. this leakage current I_CEO is not only due to the thermally generated minority carriers (I_CBO) across the C - B junction but also due to the movement of holes that flow across the base-emitter junction.

Current components of NPN transistor are shown below

Concept:

The maximum unambiguous range of pulse radar is given as:

Where,

c = speed of light

PRT = pulse repetition time

PRF = pulse repetition frequency

Calculation:

Given:

Range = 60 km

PRF = 2.5 × 103 pps

• The errors of instruments can be determined by a process known as calibration.
• Calibration is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy.
• If the difference between the measured value and the pre-defined calibrated value are outside the acceptable range, then the instrument is said to be producing error in its measurement.

Additional Information

• Slip gauges or gauge blocks are used as standards for precision length measurement.
• A optical projector is an optical device which is used to enlarge the image.

The correct answer is option '3'.

Concept:

Mutual inductance:

• When two coils are brought in proximity with each other the magnetic field in one coil tends to link with the other.
• It leads to the generation of voltage in the second coil.
• This property of a coil that affects or changes the current in the second coil is called mutual inductance.
• Mathematically, mutual inductance (M) between two coils of inductance, L₁ and L₂ is given by

... (1)

where K is the coefficient of coupling.

K ranges from 0 to 1.

Given:

L₁=5 H and L₂=20 H.

Here K=1.

From 1, mutual inductance (M) can be given as

  H

  H

= 10 H.

The correct answer is total internal reflection.

Key Points

• Optical fiber:
  • The working of an optical fiber is based on total internal reflection. Hence, option 2 is correct. 
  • Optical fibers consist of many long high-quality composite glass/quartz fibers. Each fiber consists of a core and cladding.
  • The refractive index of the core (μ1) material is higher than that of the cladding (μ2).
  • When the light is incident on one end of the fiber at a small angle, the light passes inside, undergoes repeated total internal reflections along with the fiber, and finally comes out.
  • The angle of incidence is always larger than the critical angle of the core material concerning its cladding.
  • Even if the fiber is bent, the light can easily travel through along the fiber.
• 

Pulse-code modulation(PCM):

• Pulse-code modulation (PCM) is a process used to digitally represent sampled analog or continuous-time signals.
• It is the reference form of digital in computers, CDs, digital telephony, and other digital audio applications. 
• The amplitude of the continuous-time signal is sampled at uniform intervals and each sample is quantized to its nearest value within a predetermined range of digital levels.

Time-division multiplexing(TDM):

Time-division multiplexing (TDM) is a process of transmitting and receiving independent signals over a common signal path by means of synchronized switches at each end of the transmission line so that each signal appears on the line only a fraction of time in an alternating pattern.

​PCM-TDM system:

• PCM with time-division multiplexing, transmissions from multiple sources occur in the same facility but not at the same time.
• The multiplexer is simply an electrically controlled digital switch with two inputs and one output.
• One 8-bit PCM code from each channel (16-bits total) is called a TDM frame, and the time it takes to transmit one TDM frame is called frame time.
• The frame time is reciprocal of the sample rate.
• The PCM code for each channel occupies a fixed time slot within the total TDM frame.
• Output data ratio(R_b) = 1 / T_b . Where T_b is time for each bit.

Calculation:

Given that 

Each frame consists of 24 8-bit words, plus a single synchronizing bit.

Total number of pulses sent over sampling period = 24 × 8 + 1 = 193

Sampling frequency (f_s) = 8 kHz

Sampling Time(T_s) = 1 / f_s = 1 / 8 kHz = 0.125 ms

Time for each bit(T_b) = T_s / 193 = 0.648 μs

Output data ratio(R_b) = 1 / T_b = 1 / 0.648 μs = 1.544 mbps ≈ 1.6 × 10⁶ bits/sec.

Alternative method:

R_b = sampling frequency × total number of pulses over T_s 

= 8 × 10³ × 193 

= 1.544 mbps ≈ 1.6 × 10⁶ bits/sec

Concept:

Time Scaling property

Consider the signal x(t) then the Fourier Transform will be X(ω)

Consider the signal which is scaled by ‘α’ as x(αt). Then the Fourier Transform will be

Consider the signal as shown:

The compressed signal is:

The expanded signal is:

Analysis:

 If x(t) ↔ X(ω) then Fourier transform of x(αt) is;

Case 1: For a positive real constant α

Change of variable is performed τ = αt, which yields dτ = α dt

τ → - ∞ as t → - ∞ and τ →  ∞ as t →  ∞

Case 2: For a negative real constant α

Change of variable is performed τ = - αt, which yields dτ = - α dt

τ → - ∞ as t → ∞ and τ →  ∞ as t → - ∞

Combining two cases, we have

 NOTE:

Time compression of signal results in spectral expansion.

Time expansion of signal results in spectral compression.

Answer:

Given signal is v(t) having the F.T as V(f).

The signal scaled by a factor 2 then F.T is given as v’(f).

By using property we get v’(f) as:

Conclusion: From the above transformation we can conclude that magnitude scaled by 0.5 and bandwidth increased by 2 times.

The correct answer is Persistent TCP connection, non-persistent TCP connection.

Key Points

• File Transfer Protocol or FTP is an application layer protocol and is used to communicate and transfer files between different systems on a TCP/IP protocol over the internet. It is a standard protocol for transmitting files from one host to another.
• It is also used for downloading files from servers to computers. Two computers can have different file conventions and different ways to represent data. This creates a problem while transferring.
• FTP overcomes these issues by establishing two connections between hosts. One is used for data transfer and the other connection is used for the control connection.
• For sending the actual file, the data connection is used. This connection is made between the data transfer process. For this non-persistent connection is used.
• Through control connection, we can send control information like user credentials, commands to change the remote directory, commands to retrieve and store files etc. For this FTP uses a persistent connection. Hence Option 2 is correct.

Additional Information

• FTP is one of the fastest and most efficient ways to transfer files from one computer to the other. The size limit of the file to be transferred is 2GB.
• Persistent connection or HTTP persistent connection is a communication channel that remains open for further HTTP requests and responses.
• Non-persistent connection is a channel that maintains no information about the previous requests.

From the options given, it can be guessed that the parts labelled P, Q, R, S can be ordered to form a meaningful sentence as
It is easier → for men→ to venture into space → than to explore→beneath their feet.
so order is QPSR.

Given Statement: P < Q < R < S = T

Conclusion:

I. Q < T → True (As, Q < R < S = T → Thus, it is clear that Q < T. So, the conclusion is true)

II. P > S → False (As, P < Q < R < S → Thus, it is clear that P < S. So, the conclusion is false)

III. R = T → False (As, R < S = T → Thus, it is clear that R < T. So, the conclusion is false)

Hence, the correct answer is "Only conclusion I follows".

The passive voice of imperative sentences which suggest order, suggestion or request can be made in two ways:

Active: Verb + object

Passive:

Let + object + be + past participle
You are requested/ ordered/ suggested + to + verb (Ist form) + object
Going by first way of passive voice, the passive voice of the given sentence would be: Let the door be shut.

The sentence is in active voice and to convert it in passive voice the predicate of the sentence becomes the subject.
Use structure “auxiliary + past participle”
As per the given above sentence is given in Passive Voice.
The dog was taken for a walk by her.
Hence , required answer will be option C .

i) Mr. X walks 10 km towards the North.

ii) From there it is 6 km towards the south then moves 3 km to the east.

According to the information given in the question, we can draw the following diagram.

Thus we can see he is standing in a North-East direction from his starting point.

Hence, the correct answer is "North-East".

As all terms given in the question are medical terms and Hematology is also medical term.