BEL Trainee Engineer Electronics Mock Test - 5 - Electronics and Communication Engineering (ECE) MCQ

The maximum radar range is given by:

Where

P_t is the transmitted power

A₀ is capture area

S = effective area

P_min = minimum power at the receiver which can be recognized

λ = wavelength of EM radiation

Concept:

If we pass the input signal to a single T-flip flop, we will get half of the frequency at the output.

Similarly, when we pass the input signal to n-T flip-flops, the output frequency (f_out) will be:

Application:

Given Input frequency f = 200 Hz

f_out = 25 Hz

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

Bandwidth in AM = 2f_m = 6 kHz

f_m = 3 kHz

Upper sideband = f_c + f_m = 600 kHz

∴ The carrier frequency is:

f_c = 600 – f_m = 600 - 3 kHz

f_c = 597 kHz

The reflection coefficient at the load is defined as:

 where Z_L = load impedance and Z₀ = characteristic impedance.

Also, VSWR 

Clearly, VSWR is a function of Z_L and Z₀.

For the given transmission line, Z₀ = Z_t and Z_L = Z_L

So, VSWR is constant and it doesn’t change with the length of the line, In the smith chart, this is represented as a constant VSWR circle.

• In electronics, a super-heterodyne receiver uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency and audio stage does not need alignment in a radio receiver.
• Audio mixing is one of the applications where two different audio frequencies are mixed using super-heterodyne receiver. 

Norton's Theorem states that it is possible to simplify any linear circuit, no matter how complex, to an equivalent circuit with just a single current source and parallel resistance connected to a load.

Step 1

Calculate open voltage Circuit, V_AB.

V₁ = V_AB

Step 2

Short Circuit Current 

7V₂ - 10 = 0

Concept:

Superposition theorem:

The superposition theorem states that the response of any circuit with multiple voltage and current sources is equal to the algebraic sum of the response produced by individual sources.

Calculation:

Case 1: When 5 V is active:

Applying KVL in loop ABEA:

-5 + 2I₂ + 6I = 0

2I₂ + 6I = 5........(i)

Applying KVL in loop ABCEA:

-5 + 2I₂ + 4I₂ - 4I  = 0

6I₂ - 4I = 5..........(ii)

Solving (i) and (ii), we get:

I₂ = 1.13 A

I = 0.454 A

Case 2: When 10 V is active:

Applying KVL in loop ABEA:

-10 + 4I₂ + 6I = 0

4I₂ + 6I = 10..........(i)

Applying KVL in loop ABCEA:

-10 + 4I₂ + 2I₂ - 2I  = 0

6I₂ - 2I = 10..........(ii)

Solving (i) and (ii), we get:

I₂ = 1.81 A

I = 0.454 A

I_net = 0.454 + 0.454

Inet = 0.908 A

The correct answer is Queue Organization.

Key Points

• Computer organization deals with the components of the connections, and behavior of a computer as seen by the user.
• It deals with low-level design issues. The important components of a computer organization are ALU. CPU, memory organization.
• There are three types of computer organization based on the address fields: Single Accumulator organization, General register organization, and Stack organization. Hence option 2 is correct.
• In a Single accumulator organization, the register is used implicitly to process the instructions of a program and store the results in the accumulator.
• The instruction format used in this organization is one address field and hence the Central Processing Unit (CPU) is called one address machine.
• In this, the first ALU operand is stored in the accumulator and the other is either in registers or memory.

Additional Information

• A register is a high-speed temporary storage found in the CPU which speeds up the implementation of programs.
• In General register organization, multiple general-purpose registers are used instead of a single accumulator.
  • Here the computer uses two or three address fields in their instruction format.
• The Stack organization is also called Last In First Out (LIFO) which means the last stored element will be retrieved first.
• The ALU operations are performed on stack data. Both operands are always required on the stack, after the operation, the result is placed in the stack.

Concept 

Zener Diode

• Zener diodes are specially designed to give accurate and stable reverse breakdown voltage.
• When it is forward-biased, it behaves like a standard diode.
• When reverse-biased, a small leakage current flows through it.
• If the reverse voltage across Zener diode is increased, a value of voltage will be attained at which reverse breakdown occurs.
• As the breakdown occurs, a sudden increase in current takes place called as Zener Current.
• Application: Voltage Regulator.

Zener Breakdown:

• Zener diode is a highly doped PN junction diode, due to which the depletion region between P and N becomes very narrow and the electric field is quite high.
• The breakdown easily occurs in reverse biased conditions because of the narrow junction in Zener Diode.
• Even though the electric field is very high, the electrons can tunnel through due narrow depletion region.
• In case, we narrow the space charge region, It is obvious that with the decreased reverse voltage applied reverse breakdown will occur. 
• This causes a high reverse current to flow even in the reverse bias. This can be used as a normal PN junction diode in forward bias because the junction is not destroyed.

Fig: Circuit Diagram or Layer Structure of Zener Diode

Additional Information
Difference between Zener and Avalanche Breakdown:

PWM :

It stands for pulse width modulation.

In this narrow or wide pulse is sent which means pulse width is varied.

For the generation of PWM 

• Comparator
• MonoStable Vibrator

Hence correct option is "4"

Concept:

The total memory can be calculated from the number of address lines and date-lines, i.e.

Total Memory = 2address lines × Data Lines

Also, 1 Kilo = 1 K = 210

1 Mega = 1 M = 220

1 Giga = 1 G = 230 and

1 Tera = 1 T = 240

Calculation:

Since 1 Byte = 8 bits

8 KB = 8 × 210 × 8 bits

8 KB = 213 × 8 bits

So, the Number of address lines = 13, and

Explanation:

Mechatronics is the synergistic integration of mechanical engineering with electronics and intelligent control algorithms in the design and manufacture of products processes.

Mechatronics has evolved through several stages that are primarily defined in terms of

• Primary level mechatronics
• Secondary level mechatronics
• Tertiary level mechatronics
• Quaternary level mechatronics

Primary Level Mechatronics:

• This level encompasses input/output (I/O) devices such as sensors and actuators that integrate electrical signalling with mechanical action at the basic control level. Electrically controlled fluid valves and relay switches are two examples.

Secondary Level Mechatronics:

• It integrates microelectronics into electrically controlled devices. Sometimes these products are stand-alone. An example is a cassette tape player.

Tertiary Level Mechatronics:

• This level further enhances the quality in terms of sophistication by incorporating advanced feedback functions into the control strategy.
• The mechatronic systems at this level are called smart systems.
• The control strategy uses microelectronics, microprocessors, and other application-specific integrated circuits (ASIC) as bits and pieces for control realization.
• A microprocessor-based electrical motor used for actuation purposes in typical industrial robots can be considered as an example of a tertiary level mechatronic system.

Quaternary Level Mechatronics: Intelligent control is very much a part of mechatronics now.

• Decision-making is done an influence is needed to perform the decided upon action.
• Machine or plant control intelligence is moving into the realm of human-like intelligence.
• This level attempts to improve smartness a step ahead by introducing intelligence and FDI (Fault Detection and Isolation) capability into the systems.
• At this level, mechatronics means many things to many people. Artificial Neural Networks and Fuzzy Logic try to capture some of the intellectual capabilities of intelligence.

Concept:

• Packet filter firewall can investigate up to network layer
• Packet filter firewall cannot investigate in transport layer section hence cannot block user with a specified port number

Explanation:

A packet filter network firewall can investigate and block network traffic based on several fields in a network packet header.
These fields include:

I. the source and destination port numbers.

II. the source and destination IP addresses.

Additional Information
MAC addresses are included in the packet header, they are typically used for local network communication and are not used for filtering traffic by a packet filter firewall.

Note: However, some advanced firewalls may be able to filter traffic based on the MAC address in certain scenarios, such as in virtualized environments or for wireless access points.

Hence, the correct answer is option 2.

Calculation:

Given equation is

y[n] = x[n] - x[n-1]

Applying DTFT,

Y(Ω) = X(Ω) - e-jΩX(Ω)

Y(Ω) = X(Ω)[1 - e-jΩ]

H(Ω) = e-jΩ/2[ejΩ/2 - e-jΩ/2]

H(Ω) = 2 e-jΩ/2 sin[Ω/2]

At Ω = 0 

|H(Ω)| = 0

Hence, it is a high pass filter.

Baud Rate:

• The baud rate is the rate at which information is transferred to a communication channel.
• The baud rate indicates the number of electrical oscillations per second that occurs within a data transmission.
• Baud rate is commonly used when discussing electronics that use serial communication.
• The higher the band rate, the more bits per second that are transferred.
• In the serial part content, ‘9600 band’ means that the serial port is capable of transferring a maximum of 9600 bits per second.
• At baud rates above 76,800, the cable length will need to be reduced.
• Higher the baud rate, the mere sensitive the able becomes to the quality of installation, due to how much of the wire is untwisted around each device.
• Standard baud rates include 100, 300, 600, 1200, 2400, 4800, 9600, 14400, 19200, 38400, 57600, 115200, 128000 and 256000 bits per second.

Note:

• Bit rate is the transmission of the number of bits per second whereas baud rate is the number of signal units transmitted per second.

Industrialization has a major impact on international trade.

• User data


• System data


• User program


• System stack

• User data: This includes the data that is specific to the user and is used by the user program.


• System data: This includes the data that is used by the operating system to manage the process, such as process control block (PCB), process state, priority, etc.


• User program: This is the actual program code that is executed by the processor.


• System stack: This is the stack used by the system for managing function calls and local variables.

1. Seek time: Seek time is the time taken by the disk drive to position the read/write head to the desired track on the disk. It involves moving the head arm across the platter to access the required data. Seek time is crucial because it directly affects the overall time required to access data on the disk.


2. Rotational time: Rotational time, also known as latency or rotational delay, is the time taken for the disk platter to rotate and bring the desired data under the read/write head. It depends on the rotational speed of the disk and the position of the data on the platter. It is an important factor as it contributes to the overall access time.


3. Transmission time: Transmission time refers to the time taken to transfer the data from the disk to the computer's memory or vice versa. It depends on the transfer rate of the disk and the speed of the data bus. While important, it is not specific to accessing data on the disk.


4. Waiting time: Waiting time refers to the time spent by the disk drive in handling other requests or performing internal operations before it can process the data access request. It includes time spent in the disk queue, waiting for other tasks to complete, or performing internal tasks like error correction. While it can affect the overall system performance, it is not directly related to accessing data on the disk.

The correct answer is Microsoft Outlook.

Key Points:

• Microsoft SQL Server is a relational database management system developed by Microsoft. 
• MySQL Database Service is a fully managed database service to deploy cloud-native applications. 
• Microsoft Outlook is the email service provided by Microsoft.
  • Hence this is the answer.
• Microsoft Access is the only application software you need to create apps, utilize databases, and store data in SQL Server and Microsoft Azure SQL.

The hardware that calculates CRC (Cyclic Redundancy Check) uses the following components:

• One of the primary components used in CRC calculation hardware is the shift register.


• A shift register is a digital circuit that can shift its stored bits either to the left or right, based on clock pulses.


• It is used to perform the polynomial division required in CRC calculations.

• Another important component used in CRC calculation hardware is the XOR (Exclusive OR) unit.


• The XOR unit performs the XOR operation on the input data and the feedback data in each stage of the shift register.


• This operation is necessary to generate the remainder bits in the CRC calculation process.

• The hardware used for CRC calculation combines the shift register and XOR unit to perform the required polynomial division and generate the CRC remainder bits.


• Both the shift register and XOR unit work together to calculate the CRC value.


• Hence, the correct answer is option C: Both (a) and (b).

• The instruction register is not directly involved in the CRC calculation process.


• It is a component used in a processor to hold the current instruction being executed.


• It is not related to the hardware used specifically for CRC calculation.

Name Box: This is a small rectangular box located in the top left corner of the Excel window, to the left of the formula bar. It displays the address of the currently selected cell (for example, "A1" if the first cell is selected). Apart from displaying cell references, you can use it to define names to cells or ranges.

Formula Bar: This is located just below the ribbon and to the right of the name box. It is used to enter or edit a formula, a function, or data in a cell. It displays the contents of the currently active cell and allows you to create and edit formulas.

Status Bar: This is located at the bottom of the Excel window. It provides various types of status information, including the average, count, and sum of selected numbers, whether the scroll lock is on, and other status messages. It doesn't display the address of the selected cells.

Title Bar: This is at the very top of the Excel window, displaying the name of the currently open workbook (Excel file). The title bar is largely used to move the application window around and doesn't show the address of the selected cells.

Among these options, only "Name Box" displays the reference of the currently selected cell or cells.

The triangle 6 shown in figure and another is ADB,ACB, BDC,ADC, so that total number of triangle is 10

The logic is:

Column 1: 9 × 5 × 3 = 135

Column 2: 5 × 7 × 4 = 140 

Similarly,

Let the missing number in column 3 be 'a'.

So, 5 × a × 5 = 150

⇒ 25 × a = 150

⇒ a = 150 ÷ 25

⇒ a = 6

Hence, ‘6’ is the correct answer.

The synonym of Lock, Shut and Fasten is Block.

From Statement 1:
H sits to the immediate right of D.
Two persons sit between D and F.
A is an immediate neighbour of M, who sits to the immediate right of F.

So, H sits to the immediate left of N.
The data in Statement I alone is sufficient to answer the question.
From Statement 2:
F and N are immediate neighbours and M sits immediate right of F.
A sits third to the left of N.
Here, we can not determine who sits immediate left of N.

Hence, option A is the correct answer.

As scales from an outer layer of fish similarly skin form an outer layer of man.

Hence, option A is correct.

P, Q, R, S, T, V, W, and Z are sitting around a circle facing at the centre not necessarily in this same order.

i) T is second to the right of R who is third to the right of P.

Mistake Points

Who is used for the second person in a connecting statement.

For example: 

T is second to the right of R who is third to the right of P.

Here, who is used for R and not for T.

ii) S is second to the left of P and fourth to the right of Q.

iii) V who is not an immediate neighbour of P. (This means V cannot sit immediate left or right of P).

iv) Z is third to the right of V 

Thus we can see R is second to the right of W

Hence, the correct answer is "Option 1".