MPPGCL JE Electronics Mock Test - 3 - Electronics and Communication Engineering (ECE) MCQ

Concept:

For a series RLC circuit, the net/effective impedance is given by:

X_L = Inductive reactance 

X_C = Capacitive reactance

The magnitude of the effective/net impedance is given by:

Also, the phase angle of the effective impedance is given by:

Calculation:

For a series R_L circuit, X_C = 0 Ω

Given, R = 5 kΩ and X_L = 5 kΩ

The magnitude of the net/effective impedance will be:

Putting on the respective values, we get:

Z = 5√2 = 7.07 kΩ

The phase angle of the effective impedance will be:

ϕ = 45° 

Concept:

Bitrate in the TDM system is given as:

R_b = bits per frame × frame rate

Units:

Calculation:

Given in a TDM system bitrate R_b = 32 kbps

Each slot has 16 bits i.e., each frame has 16 bits

The frame rate will be:

Frame rate = 2000 fps

Calculation:

The given situation can be visualized as shown:-

The approximate directivity is given by:

A Negative Photoresist is the one which becomes less soluble in developer when exposed to light.

While the Positive Photoresist becomes more soluble when exposed to light.

Chrome glass is used as mask for Photolythography

PUSH RP (Pre-decrement):

This instruction copies the contents of RP to stack.

For every PUSH:

• Decrement SP and PUSH RP_H
• Decrement SP and PUSH RP_L

POP RP (Pre-increment):

Used for retrieving the elements stored in the stack.

For every POP:

• Get 1 byte from stack to RP_L and increment.
• Get 1 byte from stack to RP_H and increment.

Let stack pointer (SP) = FFFF H and DE = 3025H ; HL = B315H

(a) PUSH H and

(b) PUSH D are as shown:

PUSH D: contents of DE register is copied to (FFFC and FFFB) H

PUSH H: contents of HL = B315 register, is copied to (FFFE & FFFD)H

Similarly,

c) POP J and

d) POP D are as shown:

POP H retrieves the contents to HL register

POP D: retrieves the contents to the DE register.

∴ After the execution of instructions, the contents of the DE register pair is DE = B315 H, which is

equal to HL before execution.

∴ [H] → [D]

[L] → [E]

• PSK: It stands for phase shift keying.
• In PSK, binary 1 is represented with the actual carrier, and 0 is represented with the 180^o phase shift of carrier.
• 1 is represented as  s(t) = Accos(2πf_ct)
• 0 is represented as  s(t) = - Accos(2πf_ct)
• As in PSK, one bit is transmitted in a specific time constant.
• Similarly, in 16 PSK, log₂(16) = 4 bits are transmitted in a specific time constant which is known as 16-ary PSK.

B.W. of PSK = 2R_b

Whereas for M-ary PSK,

Hence M-ary is preferred due to less bandwidth.

• In 16 APSK, Amplitude and Phase both vary in a pattern as shown in the figure.
• 16 QAM is a signal in which two carriers shifted in phase by 90 degrees are modulated and combined. As a result of their 90° phase difference, they are in quadrature.
• Often one signal is called the In-phase or “I” signal, and the other is the quadrature or “Q” signal.

Hence the given figure is 16 QAM.

So the solution is option (2).

Explanation:

Very High Frequency:

It has a range of  30 MHz to 300 MHz and are used in television broadcast.

Some ultra high frequencies are also used in television broadcasting.

Additional Information

The frequency spectrum for the complete range is:

Hence option (3) is the correct answer.

• The hybrid ring is used primarily in high-power radar and communications systems where it acts as a duplexer - allowing the same antenna to be used for transmitting and receiving functions.
• The hybrid ring is also called as rat-race circuits.
• It consists of an annular line of proper electrical length to sustain standing waves, to which four arms are connected at proper intervals by means of series or parallel junctions.

• A duplexer is an electronic device that allows bi-directional (duplex) communication over a single path.
• In radar and radio communications systems, it isolates the receiver from the transmitter while permitting them to share a common antenna.
• Most radio repeater systems include a duplexer.

Since output of system for any value of n is only depends on values of input at n or previous values the system, it is causal system

3y[n] = 2y [n - 2] – 2x[n] + x [n - 1]

Taking z – transform

3y[z] = 2y (z) z ^{- 2} – 2x[z] + x (z) z ^{- 1}

It has poles at

Since poles lie in unit circle |z_p| < 1 the system is stable

Logic families are the logic circuits having identical electrical parameters.

• It is a group of compatible ICs with the same logic levels and supply voltages for performing various logic functions.
• They are fabricated using a specific circuit configuration which is referred to as a Logic family.
• The logic family is designed by considering the basic electronic components such as resistors, diodes, transistors, and MOSFET; or combinations of any of these components.

Different logic families of digital ICs that have been introduced commercially are listed in the table.

TTL:

Important Point

The differences between different logic families are as follows:

Concept:

Propagation constant for the transmission line is given by:

For lossless line α = 0

If R ≪ ωL and a ≪ ωC, the propagation constant becomes:

   ---(1)

Comparing equation (1) with α + jβ:

α = 0. Hence the line is lossless.

Important points:

A transmission line is also lossless when:

R = 0 and G = 0.

Here also α = 0 and the line is lossless

∴ The conditions for lossless line includes:

1) R = 0; G = 0, or

2) ωL ≫ R & ωC ≫ G

Concept:

Classification of instruments on the basis of damping:

1.) Overdamping:

• The value of the damping ratio is greater than 1.
• In case of overdamping, the instrument will become slow and lethargic and rise very slowly from its zero position to a steady state position.

​2.) Undamped:

• The value of the damping ratio is equal to 0.
• In this case, the instrument never settles down and always oscillates about its mean position.

3.) Under-damped:

• The value of the damping ratio lies between 0 to 1.
• In this case, the system initially oscillates about its mean position but settles down to a steady state.

4.) Critical-damping:

• The value of the damping ratio is equal to 1.
• This damping returns the system to equilibrium as fast as possible without any oscillations.

Concept:

ALU (Arithmetic logic unit) is a circuit to perform arithmetic and logic operations.

Explanation:

• ALU uses accumulator (a register) for storing intermediate results of arithmetic and logic operations.
• Control unit provides the data to the ALU and directs the ALU to perform specific operations.
• ALU stores the result in accumulator which is a type of register. Accumulator is a kind of temporary storage device which stores the intermediate results and if some previous results are already stored on the accumulator then it automatically overwrites the new results and previous results are removed.

Scattering:

• Scattering is the loss of signal caused by the diffusion of a light beam, where the diffusion itself is caused by microscopic variations in the transmission medium
• Scattering typically happens when a light signal hits an impurity in the fibre

Dispersion:

• Dispersion is defined as pulse spreading in an optical fibre
• As a pulse of light propagates through a fibre, elements such as numerical aperture, core diameter, refractive index profile, wavelength, and laser linewidth cause the pulse to broaden

Attenuation:

• The attenuation of an optical fibre measures the amount of light lost between input and output
• Total attenuation is the sum of all losses
• For a given fibre, these losses are wavelength-dependent

Inter-symbol Interference:

• This is the effect of dispersion on optical fibre
• Intersymbol interference occurs when the pulse spreading caused by dispersion causes the output pulses of a system to overlap

The correct answer is option 1 i.e ROM

The startup instructions are stored on ROM in a computer. It is a part of BIOS (Basic Input Output System)

• At the transmitter the amplitude of the modulated signal is constant, noise and interfering stations produce amplitude changes on the modulated signal
• The purpose of the limiter is to provide a constant level of the signal to the FM demodulator, thus reducing the effect of signal level changes in the output

Concept:

Any given signal x(t) can be written as the sum of its even part and odd part, i.e.

x(t) = xe(t) + xo(t)

xe(t) = Even part of g(t) calculated as:

xo(t) = Odd part of x(t) calculated as:

Calculation:

Given:

x(t) = (2 + sin t)²

x(t) = 4 + sin²t + 4 sin t

x(-t) = 4 + sin2t - 4 sin t

Even part of g(t) calculated as:

= 4 + sin2t

Odd part of x(t) calculated as:

= 4 sin t

Hence, option A is correct.

Using Rule 1 :
1st number × 2nd number = L.C. M. × H.C.F,
First number × Second number = HCF × LCM

Following the common explanation, we get “C and Z sits two places away from Y”.
Hence, option D is correct.
Final Arrangement:

Common Explanation:
References:
1. Two people are sitting between A and Z.
2. C sits fourth to the right of Z.
3. The number of people sitting to the right of A is the same as the number of people sitting to the left of Z.
4. The number of people sitting between A and C is the same as the number of people sitting between X and C.
5. X is an immediate neighbour of D, who sits on one of the ends.
6. The number of people sitting between D and C is the same as the number of people sitting between C and Y.
7. At most 25 people are sitting in a row.
Inferences:
From reference 1, we get two possible cases.
From reference 7, case2 was eliminated.
Hence, Case 1 is the final arrangement.

During that time Lenin introduced the idea of a socialist, cooperative economy and emphasized collectivisation .Hence, these values inspired Indians to set up a socialist economy.

The correct answer is the Blackbuck.

Important Points

• The Blackbuck is the state animal of Haryana. In India hunting of Blackbuck is ban under the Wildlife Protection Act of 1972, due to excessive hunting and habitat degradation of Blackbucks during the 20th century.
• The Blackbuck or an Indian antelope are found in India, Nepal, and Pakistan. They have a lifespan of approximately 10 to 15 years.

Additional Information

• Black Francolin of the pheasant family is the State bird of Haryana.
• There are 2 National parks located in Haryana viz, Sultanpur National Park located in Gurugram and Kalesar National Park located in Yamunanagar.
• Chinkara also known as Indian Gazelle is the state animal of Rajasthan.

Hence, Option B is correct.

Checking Statement I:

Using the above references, we get the following arrangement:

Clearly, D was born in July.

Hence data in statement I is sufficient to answer the question.

Checking Statement II:

Using the above references, we get the following arrangement:

Clearly, D was born in July.

Hence data in statement II is sufficient to answer the question.

Here, the data in either Statement I or II alone is sufficient to answer the question.

Hence, Option C is correct.

Kalu’s speed = 3 m/s.
For 1200 m, Kalu would take 400 seconds and Sambhu would take 10 seconds less. Hence, 390
seconds.

As the cry of 'Dog' is called 'Bark' in the same way the cry of 'Goat' is called 'Bleat'.

The number of students who play both the games = (30 + 50 + 40)% – 100% = 20%
Hence, Option D is correct.

From Statement 1:
A sits to the immediate left of C.
D sits second to the right of A.

From the statement, we cannot determine who sits second to the right of B.
From Statement 2:
D sits immediately between E and B.
B sits to the immediate left of A.

From the statement, C sits second to the right of B.
Hence option C is correct.