MPPGCL JE Electronics Mock Test - 8 - Electronics and Communication Engineering (ECE) MCQ

Concept:

If V₀ is the initial voltage across capacitor

Calculation:

Circuit diagram at laplace domain

As capacitor was initially relaxed: V₀ = 0 (Voltage source will be replaced by a short circuit)

Given;

C = 1μF

R= 5 Ω 

Use nodal analysis at node V_C

⇒ V_C/R + V_C/(1/sC) = 10/s

⇒ V_C( 1/R + sC) = 10/s

⇒ V_C( 1+ sRC)/R = 10/s

⇒ V_C= 10R/s( 1+ sRC)

⇒ V_C= 10R/sRC( 1/RC+ s)

⇒ V_C= (10/C)/s( s+ 1/RC)

⇒ V_C = A/s + B/(s + 1/RC)

Determine the values of A and B using partial fraction

A_s=0 = (10/C)/(s + 1/RC) = (10/C)( 0 +1/RC) = 10R

B_{s= -1/RC} = (10/C)/s = -10R

⇒ V_C = (10R)/s + (-10R)/(s + 1/RC)

Using inverse laplace transform:

⇒ V_C = 10R -10Re^-t/RC

⇒ V_C = 10R(1 -e^-t/RC)

∴  V_C = 50(1 -e^-t/5)

Concept:

Drain current in saturation region is given by

Calculation:

= 1.047 mA

Control system:

A Control system is defined as a device that manages, commands direct, or regulates the behavior of other devices or systems to achieve the desired result.

It is also defined as A system with a provision for controlling the response.

There are two types of control systems.

Open-loop control system:

The open-loop control system can be described by a block diagram as shown in the figure below.

These are the systems in which the control action is independent of output.

Ex: Traffic signals, washing machine and bread toaster, systems having no sensor, etc.

Advantages:

• Simple construction and design
• Cost is less
• Maintenance is easy
• No problem of instability
• Convenient to measure when the output is difficult to measure

Disadvantages:

• These are less accurate, and their accuracy depends on the calibration.
• Inaccurate results are obtained with parameter variations within the system.
• Recalibration of the controller is required from time to time to maintain accuracy.

Closed-loop control system:

The open-loop control system can be described by a block diagram as shown in the figure below.

These are the systems in which the control action depends on the output. These systems have a tendency to oscillate.

Ex: Temperature controllers, speed control of the motor, systems having sensors, etc.

Advantages:

• More accurate
• Non-linear distortions are less
• Output is less sensitive to parameter changes within the system
• Bandwidth increases

Disadvantages:

• Design is complicated
• More expensive
• May become unstable, if there are malfunctions in the feedback.

The frequency spectrum of an Amplitude Modulated wave is given by:

Upper sideband = f_c + f_m

Lower sideband = f_c - f_m

Bandwidth in AM = Upper sideband - Lower sideband

Bandwidth = (f_c + f_m) - (f_c - f_m) = 2f_m

∴ In AM the bandwidth is equal to twice the maximum frequency component.

If sideband's highest frequency is f_m, Bandwidth is 2f_m

Concept:

EIRP: It stands for Effective isotropic Radiated power. It is defined as in dB.

EIRP = transmit power + transmitting Antenna gain - cable loss

Calculation:

Given = P_t = 40 dBW; backoff loss = 3 dB; feederloss = 3 dB

Antenna gain (G_t) = 40 dBW

EIRP = 40 + 40 - 3 - 3 = 74 dBW

1) Handoff operation involves identifying a new base station

2) It also requires that the voice and control signal be allocated to channels associated with the new base station.

3) The dwell time describes the amount of time a mobile spends in a radio cell.

4) The dwell time depends on various parameters like velocity of the user, cell size, cell shape and the traversed path.

Lissajous pattern

• When two sinusoidal signals of the same frequency and magnitude are applied to the CRO, the pattern of figures is formed. These figures are Lissajous patterns.
• The shape of these figures depends upon the phase difference of the applied two input signals.
• If the phase difference between the two signals is 0°, then the Lissajous pattern will be a straight line with a major axis in the 1^st and 3^rd quadrants.
• If the phase difference between the two signals is 90° and 270°, then the Lissajous pattern will be a circle.
• If the phase difference between the two signals is 180°, then the Lissajous pattern will be a straight line with a major axis in the 2^nd and 4^th quadrants.

Statement a:

Advanced Mobile Phone System (AMPS) is a second-generation cellular phone system.

This is statement incorrect

Reason:

• An advanced mobile phone system is an analog cellular system. It uses FDMA to separate channels in a link. It operates in ISM 800 MHz band.
• It uses two separate analog channels one for forwarding communication and one for reverse communication.
• It is a first-generation cellular phone system. So, the given statement is incorrect.

Statement b:

IS - 95 is a second-generation cellular phone system based on CDMA and DSSS.

This statement is correct

Reason:

• IS – 95 is a second-generation cellular phone system.
• It is based on CDMA and DSSS. It uses two bands for duplex communication. IS 95 has two different transmission techniques: one for use in the forward direction and another in a reverse direction.
• In this, each voice channel is digitized. It uses FDMA to separate channels in the link.

Statement c:

The Third-generation cellular phone system will provide universal personnel communication.

This statement is correct

Reason:

Program counter for any counter Stores the address of the next instruction to be executed.

Additional Information

Program counter:

• It is a 16-bit register as 8085 has 16 address lines. The program counter is updated by the processor and points to the next instruction after the processor has fetched the complete instruction.
• A program counter is used to keep track of the execution of the program. It contains the memory address of the next instruction to be fetched.
• The program counter contains the address of the next instruction to be fetched from the main memory when the previous instruction has been successfully completed.
• The program counter also functions to count the member instruction.
• As each instruction gets fetched, the program counter increases its stored value by 1.

In TV Transmission the use of FM is made for Audio transmission and AM for Video transmission.

Vestigial Sideband Modulation (VSB) is used for video modulation in TV transmission due to the following reasons :

• Video signal exhibits a large bandwidth and significant low-frequency content which suggests the use of VSB.  
• VSB (vestigial sideband) transmission transmits one sideband fully and the other sideband partially thus, reducing the bandwidth requirement.
• The circuitry for demodulation in the receiver should be simple and therefore cheap. VSB demodulation uses simple envelope detection.

The spectrum of a vestigial sideband is as shown:

Advantages of FM over AM are:

• Improved signal to noise ratio (about 25dB) w.r.t. to manmade interference.
• Smaller geographical interference between neighboring stations.
• Less radiated power.
• Well defined service areas for given transmitter power.
• The transmitted power can be used only for significant sidebands. This helps in less power distributed to the carrier and the majority of the power to the sidebands that are actually transmitting the power. This results in an efficient use of power. (Statement 3 is correct)

Disadvantages of FM:

• Much more Bandwidth (as much as 20 times as much). The theoretical bandwidth requirement is infinite.
• More complicated receivers and transmitters required.

Other important differences are elaborated in the table below:

The Infinite impulse response (IIR) filter is a recursive filter in which the current output of the filter is computed by using the current and previous inputs and outputs.

IIR filters are linear low pass filters that are represented as:

(OR)

y(n) = b₀ x(n) + b₁ x(n - 1) + …+ b_m x(n - M) – a₁ y(n - 1) ….a_Ny(n - N)

The transfer function of the above difference equation is given by:

Analysis:

Gate 1 is buffer. Input to buffer is A̅ , Output = A̅ 

Gate 2 is buffer. Input to buffer is B̅ , Output = B̅ 

Gate 3 is OR gate. Input = A̅ and B, Output = A̅ + B

Gate 4 is OR gate, Input = A and B̅ , Output = A + B̅ 

Gate 5 is AND gate, Input = (A̅ + B) and (A + B̅ ), the final output:

x = (A̅ + B) (A + B̅ )

x = A̅ B̅ + A B

Key Points

AND Gate: The Logic AND Gate is a digital logic circuit whose output HIGH only when all the inputs are 1 (HIGH) otherwise output will be LOW.

OR Gate: The Logic OR Gate is a digital logic circuit whose output goes HIGH only when any one or more than one of its inputs is HIGH.

NOT Gate: The Logic NOT Gate is the most basic of all the logic gates and is often referred to as an Inverting Buffer or simply an Inverter.

NAND Gate: The logic Gate is obtained after adding NOT Gate after AND Gate.

NOR Gate: The logic Gate is obtained after adding NOT Gate after OR Gate.

Resistance:

• If the pure resistive element is present in the circuit, then the current is in phase with the voltage.
• The power factor, in this case, is unity.

Inductance:

• If the pure inductive element is present in the circuit, then the current lags the voltage by 90 degrees.
• The power factor in this case is lagging.

Capacitance:

• If the pure capacitive element is present in the circuit, then the current leads the voltage by 90 degrees.
• The power factor, in this case, is leading.

FSK (Frequency Shift Keying):

It is used in the voice frequency telegraph system and for wireless telegraphy in the high-frequency bands. 

In FSK (Frequency Shift Keying) binary 1 is represented with a high-frequency carrier signal and binary 0 is represented with a low-frequency carrier, i.e. In FSK, the carrier frequency is switched between 2 extremes.

For binary ‘1’ → S₁ (A) = A (cos 2π f_Ht)

For binary ‘0’ → S₂ (t) = A (cos 2π f_Lt)

 The constellation diagram is as shown:

∴ Option 2 is the most appropriate. 

Notes:

Radio transmission: The two most common types of modulation used in radio are amplitude modulation (AM) and frequency modulation (FM).

Telephony: The type of modulation used in digital telephony is Pulse code modulation (PCM). 

Television: For television broadcasting, Vestigial sideband modulation is used for video transmission and Frequency modulation is used for audio transmission.

Concept:

Calculation:

Concept:-

Buses:- A bus is a high-speed internal connection. Buses are used to send control signals and data between the processor and other components. A bus, for instance, carries data through the motherboard between a CPU and the system memory.

Key Points

• Address bus carries memory addresses from the processor to other components such as primary storage and input/output devices.
• A computer bus is also known as a local bus, data bus, or address bus, a bus is a link between components or devices linked to a computer.
• A bus is a communication system in computer architecture that transfers data between components inside a computer, or between computers.
• A bus is a group of lines/wires which carry computer signals. 

Additional InformationThree components of a bus:- 

1. The address bus, a one-way pathway that allows information to pass in one direction only, carries information about where data is stored in memory.
2. The data bus is a two-way pathway carrying the actual data (information) to and from the main memory.
3. The control bus holds the control and timing signals needed to coordinate all of the computer's activities. 

PMMC instruments:

• The scale is uniform (Linear scale)
• High torque to weight ratio compared to all the other type of instruments
• Frequency error or reactance error is absent
• High sensitivity
• Hysteresis loss is lesser
• No internal heating problem
• High accuracy
• Very less power consumption

Important Points

Moving Iron (MI) type instruments:

• Moving Iron (MI) type instruments can be used for both AC & DC measurements. But Moving Iron connected through the current Transformer block DC supply. So that Moving Iron connected through the current Transformer is only used for AC measurements.
• The moving iron meter has a large magnetic reluctance as compared to the PMMC meter. That’s why more power is required to operate the moving iron meter.

Additional Information
Comparison of Moving Coil, Dynamometer type and Moving  Iron Voltmeters and Ammeters:

Explanation:

Any laplace domain function into z-domain we need a conversion.

z-transform: Any discrete sample in z-domain.

Laplace transform: Any continuous time signal into lapalce domain.

For conversion we take e^sT = z

taking log on both sides

ln (e^sT) = ln z

sT = ln z

s = (ln z)/T

Immediate addressing mode:

It is the simplest form of addressing mode, in which the operand value is present in the instruction. This mode is used to define and use constants or set initial values of variable. In this, no memory reference other than the instruction fetch is required to obtain the operand.

Implied addressing mode:

In this, operands are specified in the definition of instruction. It is used for zero address instructions.

Register addressing mode:

In register addressing mode, the address field refers to a register rather than a main memory address. In this, only a small address field is needed in the instruction and no time-consuming memory references are required.

Index addressing mode:

The correct answer is option 2.

Maxwell’s inductance bridge is used for the measurement of the self-inductance of the circuit.

The quality factor is measured for a coil, which is the combination of inductance and capacitance.

Hence, it is measured by the Maxwell Inductance Capacitance bridge.

Measurement of resistance, inductance, and capacitance

From Statement I:

From this statement, we get that Madhavi joined the office on 5th, 6th, 7th, 8th or 9th November.

Clearly, data in statement I alone is not sufficient to answer the question.

From Statement II:

From this statement, we get that Madhavi joined the office on 8th, 9th, 10th or 11th November.

Clearly, data in statement II alone is not sufficient to answer the question.

Checking both Statement, I and II together:

We can say that Madhavi joined the office either on 8th or 9th November.

Clearly, data in both the statements I and II together is not sufficient to answer question.

Hence, option D is the correct answer.

As 'Flower' is made from 'Bud' similarly 'Fruit' is made from 'Flower'.

The logic followed is:

Therefore, the number of students in the group are 20 + 30 + 70 = 120

The number of students = 120

Hence, the correct answer is "120".

Incentive means a thing that motivates or encourages someone to do something
Some of its synonyms are inducement, motivation, motive, reason, stimulus, stimulant, spur, impetus, encouragement
He had no incentive to work after he was refused a promotion
Companies provide various incentives to attract and retain talent

Repeal: To revoke or annul a law, regulation, or decision, typically through official or legislative means.

1. Sanction:

   • As a verb: to give official permission or approval for an action.
   • As a noun: a penalty or measure taken against someone who has violated a rule or law.

2. Perpetuate: To make something continue indefinitely; to sustain or prolong.

3. Pass:

   • As a verb: to approve or adopt a proposal or legislation.
   • As a noun: a successful attempt to achieve something; also, a document or ticket granting authorization or access.

4. Cancel: To revoke or annul something previously scheduled, arranged, or agreed upon; to declare null and void.

Correct option D

B is the correct option.Some seats are reserved in Lok Sabha for the members of the Schedule Castes and Scheduled Tribes. As per the order issued by the Delimitation Commission in 2008 , 412 are general, 84 seats are reserved for Scheduled Castes and “47 seats” for the Scheduled Tribes.

The correct order will be:
They felt safer → as they settled down  (R)→ to watch the mountain (P)→ from a distance (S)→ of more than five miles.(Q)