Explanation:

Unshielded Twisted Pair (UTP) Cables

Definition: Unshielded Twisted Pair (UTP) cables are a type of twisted pair cables that are commonly used for various telecommunications and networking applications. They consist of pairs of wires twisted together to reduce electromagnetic interference (EMI) from external sources and crosstalk between adjacent pairs within the cable.

Working Principle: UTP cables work by twisting the pairs of wires together, which helps to cancel out electromagnetic interference (EMI) from external sources and minimize crosstalk between the pairs. The twisting of the wires causes the magnetic fields generated by the current in each wire to cancel each other out, thus reducing the overall EMI.

Advantages:

• Cost-effective: UTP cables are generally less expensive than shielded cables, making them a popular choice for many networking applications.
• Ease of installation: UTP cables are lighter and more flexible, making them easier to install and handle compared to shielded cables.
• Widely used: UTP cables are commonly used in local area networks (LANs) and other telecommunications applications.

Disadvantages:

• Susceptibility to EMI: UTP cables do not have shielding, which makes them more susceptible to electromagnetic interference (EMI) compared to shielded cables.
• Limited distance: UTP cables are typically used for short-distance communication due to their susceptibility to EMI and signal attenuation over longer distances.

Applications: UTP cables are widely used in various applications, including local area networks (LANs), telephone systems, and other telecommunications infrastructure where cost and ease of installation are important considerations.

Correct Option Analysis:

The correct option is:

Option 1: They have a higher resistance to EMI than STP cables.

This option is incorrect because UTP cables do not have shielding, which makes them more susceptible to electromagnetic interference (EMI) compared to Shielded Twisted Pair (STP) cables. STP cables have a layer of shielding that provides additional protection against EMI, making them more resistant to interference than UTP cables. Therefore, it is not true that UTP cables have a higher resistance to EMI than STP cables.

Important Information

To further understand the analysis, let’s evaluate the other options:

Option 2: They are commonly used in local area networks (LANs).

This option is true. UTP cables are indeed commonly used in local area networks (LANs) due to their cost-effectiveness, ease of installation, and adequate performance for short-distance communication needs.

Option 3: They are lighter and more flexible than STP cables.

This option is also true. UTP cables are lighter and more flexible than STP cables because they do not have the additional shielding layer present in STP cables. This makes UTP cables easier to handle and install.

Option 4: They are cost-effective for short-distance communication.

This option is true as well. UTP cables are cost-effective for short-distance communication because they are less expensive to produce and install compared to shielded cables. Their performance is sufficient for many short-distance networking applications, making them a popular choice.

Conclusion:

Understanding the characteristics of UTP and STP cables is essential for choosing the right type of cable for specific applications. UTP cables, while cost-effective and easy to install, are more susceptible to EMI compared to STP cables due to the lack of shielding. This makes them suitable for short-distance communication in environments with minimal EMI, such as local area networks (LANs). On the other hand, STP cables provide better protection against EMI and are preferable in environments with higher levels of electromagnetic interference.

Detailed Solution: Port 1 in the 8051 Microcontroller

The 8051 microcontroller, a popular choice in embedded systems, has several ports, each with its own unique functionalities. Understanding the capabilities and limitations of these ports is critical for designing efficient and reliable systems. In this detailed analysis, we will delve into the features of the ports in the 8051 microcontroller, particularly focusing on Port 1, and explain why it is the correct answer to the question regarding dual functions.

Introduction to 8051 Microcontroller Ports

The 8051 microcontroller consists of four parallel I/O ports: Port 0, Port 1, Port 2, and Port 3. Each of these ports can be used for various input and output operations, and some of them have dual functions.

• Port 0: This is a dual-purpose port. When used for external memory interfacing, it acts as a multiplexed address and data bus. In other applications, it can be used as a general-purpose I/O port.
• Port 1: This port is unique in the sense that it does not have any dual functions. It is exclusively used for general-purpose I/O operations, which makes it simple and straightforward to use.
• Port 2: Similar to Port 0, Port 2 also serves dual purposes. While it can be used for general I/O operations, it also functions as the high-order address bus in external memory interfacing.
• Port 3: This is a highly versatile port with multiple dual functions. In addition to being a general-purpose I/O port, it can handle several control signals like interrupts, serial communication signals, timer inputs, and read/write control signals for external memory.

Explanation:

8051 Microcontroller Port Functions

The 8051 microcontroller is a popular microcontroller used in embedded systems due to its versatility and wide range of applications. It consists of four parallel I/O ports (Port 0, Port 1, Port 2, and Port 3), each of which can be used for various functions. Among these ports, Port 0 has a unique characteristic that allows it to function as both a bidirectional I/O port and an address/data bus for external memory access.

Port 0: Port 0 of the 8051 microcontroller is a dual-purpose port. It can be used as a general-purpose bidirectional I/O port, and it also serves as the multiplexed address and data bus when the microcontroller accesses external memory. When used as an address/data bus, Port 0 provides the lower 8 bits of the address (A0-A7) during the first part of the machine cycle and then switches to carry the data byte (D0-D7) during the second part of the machine cycle.

Detailed Explanation:

When interfacing the 8051 microcontroller with external memory, the microcontroller needs to provide the address and data to the memory chip. The 8051 uses Port 0 to achieve this by multiplexing the lower 8 bits of the address and the data. This means that the same physical pins on the microcontroller are used to carry both address and data information at different times.

During the first half of the machine cycle, Port 0 outputs the lower 8 bits of the address (A0-A7). This is achieved by enabling the Address Latch Enable (ALE) signal, which latches the address into an external latch (e.g., 74HC573). Once the address is latched, Port 0 switches to carry the data byte (D0-D7) during the second half of the machine cycle. This multiplexing allows the 8051 to use fewer pins for addressing and data transfer, making the microcontroller more efficient in terms of pin usage.

Here is a step-by-step breakdown of how Port 0 functions during external memory access:

1. Address Phase: During the first half of the machine cycle, Port 0 outputs the lower 8 bits of the address (A0-A7). The ALE signal is activated, which latches the address into an external latch. This allows the address to be held stable while Port 0 switches to data mode.
2. Data Phase: During the second half of the machine cycle, Port 0 switches to carry the data byte (D0-D7). The Read (RD) or Write (WR) signal is activated, indicating whether the operation is a read or write. The external memory chip uses the latched address and the data on Port 0 to perform the required operation.

This dual functionality of Port 0 makes it essential for interfacing the 8051 with external memory, enabling efficient address and data transfer using the same set of pins.

Analysis of Other Options:

Option 1: Port 1

Port 1 of the 8051 microcontroller is a general-purpose bidirectional I/O port. It consists of 8 pins (P1.0 to P1.7) that can be used for input or output operations. However, Port 1 does not have the capability to function as an address/data bus for external memory access. It is solely used for I/O operations and does not participate in memory interfacing.

Option 2: Port 3

Port 3 is another general-purpose I/O port with additional functionality. It has 8 pins (P3.0 to P3.7), and each pin can be used for specific alternate functions such as serial communication, external interrupts, timer inputs, and control signals for external memory. However, Port 3 does not serve as an address/data bus for external memory access. Its primary role is to handle I/O operations and provide control signals for various peripherals.

Option 4: Port 4

Port 4 is not a standard port in the original 8051 microcontroller architecture. Some extended versions or derivatives of the 8051 may include additional ports, such as Port 4, but in the context of the original 8051, Port 4 does not exist. Therefore, it cannot be considered for the functionality of an address/data bus.

Based on the detailed explanation and analysis of the options, it is clear that Port 0 is the correct choice for the port that functions as a bidirectional I/O and simultaneously acts as an address/data bus for external memory access in the 8051 microcontroller.

Explanation:

Main Role of Port 2 in the 8051 Microcontroller During External Memory Access

The 8051 microcontroller is a popular 8-bit microcontroller that was developed by Intel in 1980 for use in embedded systems. One of its key features is the ability to interface with external memory. To understand the main role of Port 2 during external memory access, it is important to have a grasp of the microcontroller's architecture and its memory interfacing capabilities.

During external memory access, the 8051 microcontroller needs to address both program (code) and data memory that are located outside the microcontroller. The addressing mechanism involves the use of a 16-bit address bus to communicate with the external memory. This 16-bit address bus is divided into two parts: the low-order address byte (A0-A7) and the high-order address byte (A8-A15). The low-order address byte is provided by Port 0, while the high-order address byte is provided by Port 2.

Port 2 is an 8-bit bi-directional I/O port, and its role during external memory access is to provide the high-order address byte (A8-A15). This allows the microcontroller to access a larger memory space by combining the high-order address byte from Port 2 and the low-order address byte from Port 0.

Let's delve deeper into the specifics of how Port 2 functions in the context of external memory access:

1. Address Latching: When accessing external memory, the 8051 microcontroller uses a multiplexed address/data bus for the lower 8 bits (Port 0). This means that the lower 8 bits of the address and the data share the same physical lines. To separate the address from the data, an external latch (often a 74LS373 or similar) is used. The Address Latch Enable (ALE) signal is generated by the microcontroller to control this latch. During the first part of the memory access cycle, the ALE signal goes high, and the low-order address byte is placed on Port 0. The latch captures this address byte when ALE is high.

2. High-Order Address Byte: While the ALE signal is high, the high-order address byte is placed on Port 2. Since Port 2 is dedicated to providing the high-order address byte, it does not need to be latched. The high-order address byte remains stable throughout the memory access cycle, ensuring that the correct memory location is accessed.

3. Memory Access: After the low-order address byte is latched and the high-order address byte is provided by Port 2, the microcontroller can complete the memory access by reading from or writing to the external memory. The data is then placed on or read from Port 0 during the appropriate phase of the memory access cycle.

4. Memory Space Expansion: By using Port 2 to provide the high-order address byte, the 8051 microcontroller can address up to 64KB of external memory (2^16 = 65536 bytes). This is essential for applications that require more memory than what is available internally on the microcontroller.

Example Scenario:

Consider a scenario where the 8051 microcontroller needs to access an external memory location with the address 0x1234. The high-order address byte is 0x12, and the low-order address byte is 0x34. During the memory access cycle, the following steps occur:

• The ALE signal goes high, and the low-order address byte (0x34) is placed on Port 0.
• The external latch captures the low-order address byte when ALE is high.
• Simultaneously, the high-order address byte (0x12) is placed on Port 2.
• The microcontroller then completes the memory access by reading from or writing to the external memory at address 0x1234.

In summary, the main role of Port 2 in the 8051 microcontroller during external memory access is to provide the high-order address byte (A8-A15). This is crucial for accessing a larger memory space and ensures that the correct memory location is accessed during read and write operations.

Explanation:

The primary purpose of the metallic shield in a coaxial cable is to protect against electromagnetic interference (EMI). Understanding the role of the metallic shield involves delving into the construction, principles, and functionalities of co-axial cables as well as the nature of electromagnetic interference.

Co-axial Cable Construction:

A co-axial cable is designed to transmit electrical signals with high efficiency and minimal interference. It consists of several layers:

• Core Conductor: The innermost part of the cable, typically made of copper or aluminum, which carries the electrical signal.
• Dielectric Insulator: Surrounding the core conductor, this layer insulates the signal-carrying conductor from the outer layers and helps maintain the integrity of the signal.
• Metallic Shield: This layer, often made of braided copper or aluminum, surrounds the dielectric insulator. Its primary function is to shield the inner conductor from external electromagnetic fields and to prevent electromagnetic interference (EMI).
• Outer Jacket: The outermost protective layer that shields the cable from environmental factors such as moisture, physical damage, and wear.

Electromagnetic Interference (EMI):

Electromagnetic interference is the disturbance generated by external sources that affect an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. EMI can degrade the performance of electrical devices, cause data loss, or create noise in communication systems. In the context of co-axial cables, EMI can introduce unwanted signals that interfere with the transmission of the desired signal.

Function of the Metallic Shield:

The metallic shield in a co-axial cable serves several critical functions:

• EMI Protection: The metallic shield acts as a barrier to external electromagnetic fields, preventing them from penetrating the cable and causing interference with the transmitted signal. This ensures the integrity and clarity of the signal, which is especially important in high-frequency applications such as television broadcasting and internet data transmission.
• Signal Containment: It also prevents the electromagnetic fields generated by the signal within the cable from radiating outward and causing interference with other nearby electronic devices and cables.
• Grounding: The shield can serve as a grounding path, providing a reference point for the signal and improving overall signal stability and quality..

Concept:

Relation between mode, median and mean is given by:

Mode = 3 × median – 2 × mean

Calculation:

Given:

Mode – median = 2

As we know

Mode = 3 × median – 2 × mean

Now, Mode = median + 2

⇒ (2 + median) = 3median – 2mean   

⇒ 2Median - 2Mean = 2

⇒ Median - Mean = 1

CONCEPT:

Coulomb's law in Electrostatics:

• Coulomb's law state’s that force of interaction between two stationary point charges is directly proportional to the product of the charges, and inversely proportional to the square of the distance between them and acts along the straight line joining the two charges.

Faraday's Laws of Electromagnetic Induction :

• Whenever the number of magnetic lines of force (magnetic flux) passing through a circuit/coil changes an emf is produced in the circuit called induced emf.

Pascal’s law:

• Pressure at each and every point in the closed fluid is same.

Charles law:

• If the pressure remaining constant, the volume of the given mass of a gas is directly proportional to its absolute temperature.
  i.e. V ∝ T

EXPLANATION:

• Coulomb’s law states that the mutual electric force between two charges q₁ and q₂ separated by r distance can be given by

Force (F) ∝ q1 × q2

\(F \propto \;\frac{1}{{{r^2}}}\)

\(F = K\frac{{{q_1} \times {q_2}}}{{{r^2}}}\)

Where K is a constant = 9 × 109 Nm2/C2

• If we want to calculate mutual electric forces between multiple charges we have to apply superposition principle along with coulomb’s law.

Here a = 2; d = 4

⇒ A40th term = a + 39d = 2 + 39 × 4 = 2 + 156 = 158

∴ Sum of 40 terms = \(\frac{n}{2}\left[ {a + A40th} \right]\)

⇒ \(Sum = \frac{{40}}{2} \times \left[ {2 + 158} \right] = 20 \times 160 = 3200\)

∴ Sum of 40 terms = 3200

CONCEPT:

• The rate of work done is called power.
• It is denoted by P. The SI unit of power is the watt (W).

Power (P) = W / t

W = work done

t = time

EXPLANATION:

Dimensions of force is \(ML{T^{ - 2}}\).

Energy or Work done = Force × Distance 

Dimensions of energy is \(M{L^2}{T^{ - 2}}\).

 The dimensions of power = (Dimension of work) / Time (t) = (\(M{L^2}{T^{ - 2}}\))/T =  \(M{L^2}{T^{ - 3}}\).

CONCEPT:

• Dispersion: The splitting of light into its component colors is called dispersion.
• Reflection: Reflection of Light is the process of sending back the light rays which fall on the surface of an object.
• Refraction: The bending of the light beam as it travels from one medium to another is known as the refraction of light.
• It takes place at the boundary between the two mediums.

EXPLANATION:

There various stages of phenomenon in the formation of a rainbow:

• The ray is first refracted at the air-droplet interface and dispersed into 7 colors.
• The dispersed rays are then totally internally reflected by the droplet-air interface.
• The dispersed rays then undergo refraction at the droplet-air interface and finally rainbow is formed.
• In this, we can see that that refraction and total internal reflection plays an important role in rainbow formation also the splitting of white light into seven colors is caused because of phenomena known as dispersion
• Thus all three phenomenon- refraction, reflection and dispersion are responsible for the formation of a rainbow in the sky. Hence option 4 is correct.

The Correct Answer is 'Cathode ray oscilloscope.'

• The waveform of a certain signal can be studied by a cathode ray oscilloscope.

Key Points

• The cathode ray oscilloscope is an electronic instrument used to obtain waveforms when the different input signals are given
  • It is also called an oscillograph
  • It is a graph plotting device that is used to measure different characteristics of signals.
  • When horizontal deflection plates and vertical deflection plates of CRO (Cathode Ray Oscilloscope) are connected to two sinusoidal voltages, the patterns that appear at the CRO screen are called the Lissajous pattern
  • The Lissajous pattern obtained in a CRO depends upon frequency, amplitude, and phase relationship
  • The patterns used to measure phase and frequency with a cathode ray oscilloscope are called the Lissajous pattern

Additional Information

• It is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum.
  • The basic function of a spectrometer is to take light in, break it into its spectral components, digitize the signal as a function of wavelength, and read it out and display it through a computer.
  • The mass spectrometer, NMR spectrometer, and the optical spectrometer are the three most common types of spectrometers found in research labs around the world.
  • The incident light from the light source can be transmitted, absorbed, or reflected through the sample.
• A p-n junction diode is a two-terminal device, which allows the electric current in only one direction while blocks the electric current in the opposite or reverse direction
  • The p-n junction, which is formed when the p-type and n-type semiconductors are joined, is called a p-n junction diode.
• A sonometer is an apparatus made of a hollow box having two holes.
  • A string is attached to it by which the transverse vibrations of strings can be studied.

Concept:

Load Power = 150 watts

Rating of battery used in UPS = 12 Volts, 150 Ah

The energy supplied by battery = Voltage x Ah

Energy supplied by battery = 12 × 150 = 1800 watt-hour

∴ A battery can supply energy of 1800 watt-hour

Backup time = (Energy supplied by the battery)/(Load Power)

Backup time \(=\frac{1800}{150}=12~h\)

Root of the equation of 2x² + 4x = 30

2x² + 4x – 30 = 0

Divided by 2

x² + 2x – 15 = 0

x² + 5x – 3x – 15 = 0

x (x + 5) – 3 (x + 5) = 0

(x + 5) (x – 3) = 0

Taking,

(x + 5) = 0

x = (-5)

Taking,

(x – 3) = 0

x = 3

So, the roots of the equation of 2x² + 4x = 30 are (-5) and 3.

Tip: To find the answer quickly we can put the values of the options directly in the equation and check whether the values satisfy the equation. 

MS WORD is an example of Application Software.

Key Points

Application Software - Application software is a program or group of programs designed for end-users. Examples of an application include a word processor, a spreadsheet, an accounting application, a web browser, an email client, a media player, a file viewer, simulators, a console game, or a photo editor.

Additional Information

1. System Software - System software is software designed to provide a platform for other software. Examples of system software include operating systems like macOS, GNU/Linux, Android and Microsoft Windows, computational science software, game engines, industrial automation, and software as a service application.

2. Operating Software - An Operating System (OS) is an interface between a computer user and computer hardware. An operating system is software that performs all the basic tasks like file management, memory management, process management, handling input and output, and controlling peripheral devices such as disk drives and printers. Five of the most common operating systems are Microsoft Windows, Apple macOS, Linux, Android, and Apple's iOS.

3. Translating Program - A translator is a programming language processor that converts a computer program from one language to another. It takes a program written in source code and converts it into machine code. It discovers and identifies the error during translation.

Thus, option 3 is the correct answer.

• The sensation of electric shock is caused by the flow of electric current through the human body to the earth.
• When a person comes in contact with electrically live objects like water heaters, washing machines electric iron, etc., the extent of damages caused by this current depends on its magnitude and duration.
• This kind of current is called the leakage current which comes in milli-amps.
• These leakage currents being very small in magnitude, hence undetected by the fuses/MCBs are the major cause for the fires due to electricity.
• Residual current operated circuit breakers provide maximum protection from electric shocks and fires caused due to earth leakage current and also prevents the waste of electrical energy.
• These residual current circuit breakers (RCCB) are popularly called as earth leakage circuit breakers (ELCB).