BEL Trainee Engineer Electronics Mock Test - 4 - Electronics and Communication Engineering (ECE) MCQ

When a carrier is modulated by different waves having different modulation indexes,

The effective modulation index is given by:

μ₁ = 0.6

μ₂ = 0.8

Concept:

The coil is a circuit with Resistance and Inductance connected in series as shown:

The time constant is defined as the time required for the circuit to reach 63% of the final value (steady-state value).

The time constant of the above L-R circuit is:

Calculation:

Given,

L = 15 H

τ = 2 sec

With 

R = 7.5 Ω 

Note:

For a series RC circuit, the time constant (τ) is given by:

τ = RC

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.

The correct answer is Syntax errors.

• A syntax error is an error in the source code of a program.
• Since computer programs must follow strict syntax to compile correctly, any aspects of the code that do not conform to the syntax of the programming language will produce a syntax error.
• Unlike logic errors, which are errors in the flow or logic of a program, syntax errors are small grammatical mistakes, sometimes limited to a single character.
• For example, a missing semicolon at the end of a line or an extra bracket at the end of a function may produce a syntax error.

Key Points

• Internal errors are due to faulty logic or coding in the program.
  • Common types of internal errors include Bounds errors, Inserting a null pointer into a collection, Attempting to use a bad date.
• A semantic error is a violation of the rules of the meaning of a natural language or a programming language.
  • semantic errors are the hardest to debug because the interpreter provides no information about what is wrong.
• A logic error (or logical error) is a mistake in a program's source code that results in incorrect or unexpected behavior.
  • It is a type of runtime error that may simply produce the wrong output or may cause a program to crash while running.

Concept:

According to Kepler’s third law of motion, the square of the time period of revolution of a planet is proportional to the cube of the semi-major axis of the ellipse traced out by the planet.

Let’s consider first for circular orbit since it's easy to grasp compared to an elliptical orbit

The time period of a satellite, 

• Geostationary Satellite: The satellite which appears stationary relative to the earth is called a geostationary or geosynchronous satellite.
• A geostationary satellite always stays over the same place above the earth's surface.
• Such a satellite appears stationary due to its zero relative velocity w.r.t. that place on earth.
• The orbit of a geostationary satellite is known as the parking orbit.
• Thus time period of a geostationary satellite is 24 hours since earth complete it’s one revolution in 24 hours

Here,

r = Distance between satellite from the center of the planet

h = Distance between satellite from the center of the planet

M = mass of the planet

m = mass of the satellite

G = gravitational constant

T = time period of a satellite to complete one revolution

Calculation:

Given that,

Initial radius of the orbit, r = 4000 km

The initial time period of a satellite, T­ = 24 hours

The final radius of the orbit, r’ = 1000 km

The final time period of a satellite, T’ = ?

Thus from the above-given explanation according to Kepler’s third law of motion, the ratio of both periods of a satellite can be expressed as

Hence option 4 is correct among all.

The correct answer is Long Term Evolution.

Key Points

• LTE Stands for Long Term Evolution, It is a wireless broadband communication. 
• It is an upgraded version of 3G mobile technology which promises data transfer rates of 100 Mbps.
• It is based on UMTS and GSM technologies.

Additional Information

• 4G stands for 4th Generation technology.
• GSM stands for Global system for mobile communication.
• UMTS stands for Universal mobile telecommunications system.
• Ravi Shankar Prasad is a telecom minister of India.

Steady-state error-

Steady-state error is defined as the difference between the input (command) and the output of a system in the limit as time goes to infinity (i.e. when the response has reached a steady-state). The steady-state error will depend on the type of input (step, ramp, etc.) as well as the system type (0, I, or II).

We can calculate the steady-state error for this system from either the open or closed-loop transfer function using the Final Value Theorem.

The steady-state error is a measure of system accuracy.

These errors arise from the nature of the inputs, system type, and from nonlinearities of system components such as static friction, backlash, etc.

These are generally aggravated by amplifier drifts, aging, or deterioration.

Measurement of power

According to Blondel's Theorem, for the measurement of power in n-phase, n-wire without neutral, (n - 1) wattmeters are required.

For measurement of power in 3-phase, (3 - 1 = 2) wattmeters are required.

The readings of both the wattmeters are given by:

The power factor is given by:

Power factor = cosϕ 

At zero power, cosϕ = 0

At, ϕ = 90°, the readings of both the wattmeters are:

Thus, W1 = -ve, W2  = +Ve 

Thus at zero power factor, the reading of both wattmeters are equal and opposite.

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.

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:

Concept:

The Carrier to noise ratio is related to the parameters by the equation:

Analysis:

All the factors such as Bandwidth, free space loss and radiated power affect the Carrier to Noise ratio. 

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 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.

Concept:

Static error (E) = Am – At

Am = Measured value

At = True value

Relative Static Error: The ratio of absolute error to the true value is called relative static error.

Limiting Error:

The maximum allowable error in the measurement is specified in terms of true value, is known as limiting error. It will give a range of errors. It is always with respect to true value, so it is a variable error.

Guaranteed Accuracy Error:

The allowable error in measurement is specified in terms of full-scale value is known as a guaranteed accuracy error. It is a variable error seen by the instrument since it is with respect to full-scale value.

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.

immigrant : a person who has come to live permanently in a country

The meaning of word Appreciation (Noun) is: Thankfulness. It’s antonym should be: Aspersions, e.g, to criticize harshly.

• Meaning of August: Respected and impressive.
• Meaning of Common: occurring, found, or done often; prevalent
• Meaning of Ridiculous: deserving or inviting derision or mockery; absurd
• Meaning of Dignified: having or showing a composed or serious manner that is worthy of respect
• Meaning of Petty: unduly concerned with trivial matters, especially in a small-minded or spiteful way

The problem of contamination of water is being faced by the people. The author says that there is poor quality of water.

The correct option is (2) Use Presenter View

Key Points

• In order to help you concentrate while presenting and engage with your audience, PowerPoint Presenter View displays the current slide, the next slide, and your speaker notes. The slide Show tab should be selected. Check the option next to Use Presenter View.
• On the ribbon, click the Slide Show tab. Choose From the Current Slide or From the Beginning. To begin the presentation, you can alternatively click the Slide Show button in the status bar or hit F5 on your keyboard.

Additional Information

• When practicing, use the Slide Timing function to record how long it takes you to present each slide. When you deliver your presentation to your real audience, you may utilize the recorded times to advance the slides automatically.
• You can record your presentation and get audio narration, slide timings, and laser pointer gestures with a microphone, speakers, and sound card.
• Do the following to demonstrate the media controls during your presentation: Choose the Show Media Controls check box under the Set up group on the Slide Show tab.

The correct answer is Both (i) and (ii)

Key PointsRuler and Gridlines are tools offered in MS-PowerPoint 2016 to help users manage and organize the content on their slides. The ruler is used to measure and line up objects, while gridlines help position text and media objects with greater accuracy by providing a visual grid on the slides.

A bug is an error or fault in a computer program that causes it to produce an incorrect or unexpected result, or to behave in unintended ways.

Virus: A virus is usually harmful and it can corrupt data, overwrite files, or use up system resources.

Bit (Binary digit): It is a digit within the binary number system. A bit is the smallest unit of the information held on a computer.

Spam: These are unsolicited e-mail advertisements, which is the internet equivalent of junk mail.

• Summary reports with good grouping: Operational managers require summary reports that provide a concise overview of key information, presented in a well-organized manner. These reports should include necessary data and present it in a way that allows managers to easily understand trends, patterns, and performance.



• Exception reports: Operational managers need exception reports that highlight any deviations from expected norms or predefined thresholds. These reports help managers identify and address any issues or anomalies, allowing them to take appropriate actions to rectify the situation.



• Detailed reports: Operational managers often require detailed reports that provide comprehensive information about specific aspects of their operations. These reports should include in-depth data, analysis, and insights, enabling managers to make informed decisions and identify areas for improvement.



• Expected reports: Operational managers rely on reports that provide them with the expected information they need to effectively manage their operations. These reports should align with the manager's specific requirements, providing them with the necessary data and insights to monitor performance, track progress, and make informed decisions.

1. Atheist: Someone who lacks belief in the existence of gods or deities and typically rejects organized religion.
   Religion: A system of beliefs, practices, and rituals centered around the worship of one or more gods or a divine power.
2. Sceptic: A person inclined to doubt or question accepted opinions and beliefs, especially those in religion or superstition.
   Pious: Devoutly religious or reverent, typically exhibiting strong religious devotion or dedication.
3. Iconoclast: A person who attacks or criticizes cherished beliefs or institutions, especially those in religion.
   Idol: An image or representation of a god used as an object of worship, or a person or thing that is greatly admired, loved, or revered.
4. Apostate: Someone who renounces or abandons a religious or political belief or principle, often after previously holding it.
   State: A politically organized community living under a government, usually sovereign, occupying a definite territory.

Both are pairs of antonyms.
Hence, Option A is correct.

As Tree is found in Forest similarly Grass is found in Lawn.

The Venn diagram that best represents the relationship between Mammals, Whale, and Elephant is shown below:

Whale and Elephant belong to the class Mammal.

Elephants are the largest land mammals on earth and have distinctly massive bodies, large ears, and long trunks.

Hence, ‘Option 1’ is the correct answer.

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