RRB ALP & Technician Practice Test - 1 - RRB Group D / RPF Constable MCQ

• Definition: The knee voltage of a silicon diode is the voltage at which the diode starts conducting significantly.


• Value: The knee voltage of a silicon diode is approximately 0.7 V.

In summary, the knee voltage of a silicon diode is an important parameter that determines its conduction characteristics. A silicon diode starts conducting significantly when the voltage across it reaches approximately 0.7 V.

• Indian National Congress in 1936: The Indian National Congress proposed for the first time to constitute the Constitution Assembly in 1936. The idea was put forward by Jawaharlal Nehru in his presidential speech.


• Objective: The main objective of forming the Constitution Assembly was to draft and enact a new constitution for India, which would serve as the supreme law of the land.


• Process: The Constitution Assembly was eventually formed in 1946 after the Cabinet Mission Plan was accepted by the Indian National Congress, Muslim League, and other parties. The members of the Assembly were elected by the provincial assemblies.


• Constitution-making: The Constitution Assembly had the task of drafting the Indian Constitution, which was finally adopted on January 26, 1950, marking the birth of the Republic of India.

Therefore, the Indian National Congress was the first organization to propose the formation of the Constitution Assembly to draft the Indian Constitution in 1936.

• Given: Voltage across inductor (V_L) = 20 V, Voltage across resistance (V_R) = 15 V


• Using Ohm's Law: V_R = I * R and V_L = I * X_L


• Impedance of Inductor (X_L): X_L = V_L / I = 20 V / I


• Impedance of Resistance (R): R = V_R / I = 15 V / I


• Total Impedance (Z): Z = √(R² + X_L²) = √((15/I)² + (20/I)²)


• Supply Voltage (V): V = I * Z


• Given that V_L = 20 V and V_R = 15 V:


• 20 V = I * (20/I) => I = 1 A


• 15 V = 1 A * R => R = 15 Ω


• Z = √((15/1)² + (20/1)²) = √(225 + 400) = √625 = 25 Ω


• V = 1 A * 25 Ω = 25 V

• Voltage Transformation: Transformers are primarily used to change the voltage levels in an electrical circuit. They can step up (increase) or step down (decrease) the voltage as needed.


• Current Transformation: While transformers do not actively change the current, they do allow for the transformation of current based on the ratio of turns in the primary and secondary coils.


• Power Transmission: By altering the voltage levels, transformers facilitate the efficient transmission of power over long distances by reducing energy losses through the use of high voltage and low current.

• Mutual Induction: Transformers operate on the principle of mutual induction, where changing current in the primary coil induces a voltage in the secondary coil.


• Core Material: The core material of a transformer, typically made of iron or steel, helps in enhancing the magnetic flux and thereby improving the efficiency of voltage transformation.


• Turns Ratio: The turns ratio of the primary and secondary coils determines the voltage transformation capability of the transformer.

• Transformers play a crucial role in the efficient distribution and transmission of electricity by transforming voltage levels while maintaining power continuity.


• Understanding the functions and working principles of transformers is essential for electrical engineers and technicians to ensure the proper operation of electrical systems.

• Definition: The power factor of a circuit is the ratio of real power to apparent power.


• Real Power: Real power is the power consumed by the circuit to perform work and is measured in watts.


• Apparent Power: Apparent power is the product of voltage and current in the circuit and is measured in volt-amperes (VA).

• For a pure resistor circuit:


• There is no phase difference between voltage and current in a pure resistor circuit.


• The power factor in a pure resistor circuit is 1 because the real power and apparent power are equal.


• Since the reactance in a pure resistor circuit is zero, the power factor is unity.

• A high power factor indicates efficient utilization of electrical power in a circuit.


• Improving power factor helps in reducing losses in the electrical system.


• Utilities often penalize low power factor, so maintaining a high power factor is beneficial.

• Safekeeping and maintenance: NSDL provides safekeeping and maintenance services for debentures in electronic form.


• Dematerialization: NSDL facilitates the conversion of physical debenture certificates into electronic form, making it easier for investors to manage their investments.


• Transfer and settlement: NSDL enables seamless transfer and settlement of debentures between investors electronically.


• Interest payment: NSDL ensures timely payment of interest on debentures to the investors in electronic form.


• Corporate actions: NSDL facilitates corporate actions related to debentures, such as redemption, bonus issue, etc., in electronic form.

• Uranus: Uranus does have a system of rings, but they are very faint and difficult to see from Earth.


• Mars: Mars does not have any rings around it.


• Jupiter: Jupiter has a system of rings, but they are also very faint and not as prominent as Saturn's rings.


• Saturn: Saturn is known for its beautiful and prominent ring system, which is easily visible from Earth. These rings are made up of ice, dust, and rock particles.

• Therefore, the correct answer is Saturn (Option D), as it is the planet known for its spectacular ring system.

• Dielectric heating:

• Dielectric heating is used to heat non-conductors.


• This method utilizes the dielectric properties of materials to generate heat.


• Dielectric heating works by applying an alternating electric field to a material, causing its molecules to align and produce heat due to molecular friction.


• Common applications of dielectric heating include microwave ovens and industrial processes that require heating non-conductive materials.


• Dielectric heating is efficient and can heat materials quickly and evenly.

Therefore, option D: Dielectric heating is the correct answer for heating non-conductors.

• Gauss: Gauss is a unit of magnetic induction, not magnetic flux density. It is equal to 1 Maxwell per square centimeter.


• Tesla: The Tesla (T) is the SI unit of magnetic flux density. It is defined as one Weber per square meter.


• Oersted: Oersted is a unit of magnetic field strength, not magnetic flux density. It is named after Hans Christian Oersted, a Danish physicist.


• Weber: Weber is the SI unit of magnetic flux, which is the total magnetic field passing through a surface. It is named after Wilhelm Eduard Weber, a German physicist.

• Magnetic flux density is a measure of the strength of a magnetic field per unit area. It is an important quantity in physics and engineering.


• The SI unit of magnetic flux density is the Tesla (T), named after Nikola Tesla, a Serbian-American inventor and electrical engineer.


• One Tesla is equivalent to one Weber per square meter, where the Weber is the SI unit of magnetic flux.


• It is important to distinguish between units such as Gauss, Tesla, Oersted, and Weber when dealing with magnetic fields and their properties.

• Most Stable: Crystalline oscillators are known for their high stability in frequency and low phase noise.


• Crystal Resonator: They use a quartz crystal resonator to generate precise frequencies.


• Temperature Stability: Crystals have very stable frequency characteristics over a wide temperature range.


• Aging: Crystals have very low aging rates, meaning they maintain their frequency stability over long periods of time.

Headquarters of Geological Survey of India:

• Location: Dehradun

Detailed

• Geological Survey of India is headquartered in Dehradun.


• Dehradun is a city in the state of Uttarakhand in India.


• The organization is responsible for conducting geological surveys and studies to assess the mineral resources of the country.


• It plays a crucial role in the exploration and conservation of mineral wealth in India.


• Dehradun, with its strategic location, provides easy access to various geological sites across the country for survey purposes.

Therefore, the correct answer is B: Dehradun.

• Designing: Signal generators are used in the design phase of electronic circuits to create specific waveforms for testing and prototyping.


• Testing: Signal generators are essential for testing the performance of electronic devices such as amplifiers, filters, and sensors.


• Repairing: Signal generators can also be used in troubleshooting and repairing electronic equipment by generating test signals to isolate faulty components.


• All the above: Signal generators have versatile applications in designing, testing, and repairing electronic circuits, making them a valuable tool for electronics engineers and technicians.

• Nasik Location: Nasik is a city located in the state of Maharashtra, India.


• River Bank: Nasik is situated on the bank of the river Godavari.


• Significance of Godavari: The Godavari river is the second longest river in India and is known for its cultural and religious significance.


• Importance of Nasik: Nasik is a popular pilgrimage destination in India and is known for its temples, caves, and festivals.


• Godavari River: The Godavari river originates in the Western Ghats of Maharashtra and flows through several states before emptying into the Bay of Bengal.

• Ashoka


• Chandragupta -II


• Kanishka


• Harsha

• Kanishka: Kanishka, the great Kushan emperor, started the Shaka era in 78 AD. The Shaka era was used as an official calendar by the Indian government for many centuries.


• Ashoka: Ashoka was an ancient Indian emperor of the Maurya Dynasty, known for his conversion to Buddhism and his efforts to spread the teachings of the Buddha.


• Chandragupta - II: Chandragupta II, also known as Chandragupta Vikramaditya, was one of the most powerful emperors of the Gupta Empire in India.


• Harsha: Harsha, also known as Harshavardhana, was an Indian emperor who ruled North India from 606 to 647 AD.

• Incomplete combustion: When a cylinder receives more fuel than required, it may not burn completely, leading to the formation of smoke in the exhaust.


• Rich air-fuel mixture: Excess fuel can result in a rich air-fuel mixture, which can cause smoky exhaust emissions.


• Increased soot formation: Over-fueling can lead to the production of more soot, which can be visible in the exhaust as smoke.


• Excessive carbon buildup: The excess fuel can result in carbon buildup in the engine, leading to smoky exhaust emissions.

Therefore, the presence of smoky exhaust is a common indicator of over-fueling in a diesel engine.

• Changing the audio frequency: The information in CW (Continuous Wave) transmission is sent by changing the audio frequency. CW transmission is a method of sending Morse code signals by varying the frequency of a continuous wave carrier signal. By changing the audio frequency, different Morse code signals can be generated and transmitted.

• Tubular centrifugal: Tubular centrifugal separators can effectively remove moisture from lubricating oil by using high centrifugal force to separate water droplets from the oil. The water is then collected and drained out of the system.



• Clarifier: A clarifier is a type of equipment that utilizes gravity to separate water from oil. The oil and water mixture is allowed to settle in the clarifier, with the water sinking to the bottom and the oil rising to the top for extraction.



• Sparkler filter: Sparkler filters use a filtering media to trap water particles present in the lubricating oil. As the oil passes through the filter, the water is captured, allowing for clean and dry oil to be collected.



• Vacuum leaf filter: A vacuum leaf filter is another method to remove moisture from lubricating oil. This filter uses a series of interconnected filter leaves to trap water particles while allowing the oil to pass through, resulting in dry oil output.

• Atomic number of Germanium: Germanium has an atomic number of 32.



• Electron configuration: The electron configuration of Germanium is [Ar] 3d¹⁰ 4s² 4p².



• Valence electrons: The valence electrons are the electrons in the outermost shell of an atom. In the case of Germanium, it belongs to group 14 of the periodic table, so it has 4 valence electrons.



• Valence electrons determine chemical properties: The number of valence electrons in an atom determines its chemical properties. Germanium, with 4 valence electrons, can form covalent bonds by sharing these electrons.

• Share of export from India: This refers to the percentage of total exports from India that go to a particular country.


• Maximum export: This means the country that receives the highest share of exports from India.


• Options: The given options are USA, UK, UAE, and Japan.

• USA: The United States is one of India's largest trading partners and receives a significant share of exports from India. It is a major market for various Indian products such as textiles, pharmaceuticals, and IT services.


• UK: The United Kingdom is also an important trading partner for India, but it does not receive as high a share of exports as the USA.


• UAE: The United Arab Emirates is a key destination for Indian exports, particularly in sectors like petroleum products, gems and jewelry, and electronics. However, it does not receive the maximum share of exports from India.


• Japan: Japan is a significant trading partner for India, especially in sectors like automobiles, machinery, and IT. However, it does not receive the highest share of exports from India.

• Therefore, based on the analysis of the options provided, the correct answer is USA as it receives the maximum share of exports from India compared to the other countries listed.

• Capacitor is used in it: This statement is incorrect. Difference amplifiers typically do not use capacitors in their design.


• Used to compare two signals: Difference amplifiers are specifically designed to amplify the voltage difference between two input signals.


• Yields more than the direct couple amplifier: Difference amplifiers generally provide higher gain compared to direct-coupled amplifiers.


• Frequency response remains flat: Difference amplifiers have a flat frequency response from zero to high frequency, making them suitable for a wide range of applications.

A difference amplifier, also known as a subtractor, is an operational amplifier circuit that amplifies the voltage difference between two input signals. It is commonly used in applications where the precise comparison of two signals is required. Difference amplifiers offer several advantages over direct-coupled amplifiers, such as higher gain and a flat frequency response.

While difference amplifiers do not typically use capacitors in their design, they are still widely used in various electronic systems due to their accuracy and reliability. The absence of capacitors in the circuit helps in maintaining a stable response across different frequencies, making difference amplifiers suitable for a wide range of applications.

• Maharashtra: The caves of Ajanta are located in the state of Maharashtra, India.

• The Ajanta Caves are a UNESCO World Heritage Site and consist of 30 rock-cut Buddhist cave monuments dating back to the 2nd century BCE to about 480 or 650 CE.


• These caves are known for their exquisite ancient paintings and sculptures that depict the life of Buddha and various stories from Buddhist scriptures.


• The caves also served as monasteries and worship halls for Buddhist monks and followers.


• Visitors can explore the intricate carvings, detailed sculptures, and vibrant paintings that adorn the walls and ceilings of the Ajanta Caves.

• Located near the village of Ajanta in Aurangabad district of Maharashtra, the caves are a popular tourist destination for history buffs, art enthusiasts, and spiritual seekers.


• Visitors can access the Ajanta Caves by road from Aurangabad city, which is well-connected by air, rail, and road to major cities in India.


• Exploring the Ajanta Caves provides a fascinating glimpse into the rich cultural and religious heritage of ancient India.

• Coal gas: Coal gas has a higher calorie value compared to the other gases mentioned. It is a byproduct of coal carbonization and contains a high percentage of hydrogen and methane, which makes it a potent source of energy.



• Producer gas: Producer gas is generated by partial combustion of solid fuels like coal or biomass. It has a lower calorie value compared to coal gas due to its composition, which includes nitrogen and carbon dioxide alongside carbon monoxide and hydrogen.



• Steam fiery gas: Steam fiery gas, also known as water gas, is produced by passing steam over hot coal or coke. It has a moderate calorie value, falling between coal gas and producer gas in terms of energy content.



• Oil gas: Oil gas is obtained by the distillation of crude oil or petroleum. It has a higher calorie value compared to producer gas but is still lower than coal gas. Oil gas is a valuable source of energy due to its composition of hydrocarbons.

Among the options provided, Producer gas has the least calorie value. While it is a useful fuel source, it falls short in terms of energy content when compared to coal gas, steam fiery gas, and oil gas.

• Given: ∫x/cos²x


• Integration by parts: To find the integral of x/cos²x, let u = x and dv = 1/cos²x dx


• Differentiate u: du = dx


• Integrate dv: v = tan x


• Apply integration by parts formula: ∫u dv = uv - ∫v du


• Substitute the values: = x tan x - ∫tan x dx


• Integrate ∫tan x dx: = -log|cos x| + C


• Therefore, the integral of x/cos²x is: x tan x - log|cos x| + C


• Comparing with the given options: x tan x + log|cos x| is the closest match, which is option C

• Battle of Plassey: The Battle of Plassey in 1757 was a significant event in the history of British India as it marked the beginning of British rule in India. However, it did not formalize the colonial system of the company.


• Battle of Buxar: The Battle of Buxar in 1764 was a decisive battle that led to the formalization of the colonial system by the East India Company. The victory in this battle allowed the company to establish its control over a vast territory in India.


• Battle of Panipat: The Battle of Panipat in 1761 was a major battle between the Marathas and the Afghan king Ahmad Shah Durrani. While it had a significant impact on the history of India, it did not directly lead to the formalization of the colonial system by the company.


• Battle of Wandiwash: The Battle of Wandiwash in 1760 was a decisive battle in the Carnatic Wars between the British East India Company and the French East India Company. While it was an important victory for the British, it did not formalize the colonial system of the company.

Therefore, the correct answer is Battle of Buxar, as it was the battle that led to the formalization of the colonial system by the East India Company in India.

• Isobutane: Isobutane is not the polymer of natural rubber.


• Isoprene: Natural rubber is a polymer of isoprene. Isoprene is a type of hydrocarbon that is the building block of natural rubber.


• Propane: Propane is not the polymer of natural rubber.


• Isopropene: Isopropene is not the polymer of natural rubber.

Therefore, the correct answer is Isoprene.

• Preferred winding: Lap winding

• Lap winding: Lap winding is generally preferred for generating large currents on D.C. generators because it allows for a higher current-carrying capacity. In lap winding, the end of one coil is connected to the beginning of the next coil, resulting in all coils being in parallel. This parallel connection increases the total current capacity of the generator.


• Progressive wave winding: While progressive wave winding is also used in some cases, lap winding is more suitable for generating large currents due to its parallel connection of coils.


• Retrogressive wave winding: Retrogressive wave winding is not preferred for generating large currents as it does not provide the same level of current-carrying capacity as lap winding.


• Current depends on design: While the design of the generator can impact the current output, lap winding is generally the preferred choice for generating large currents.

• A.C. Servomotor: A.C. servomotor is a type of motor that is specifically designed for high-precision control applications where accurate positioning, speed, and torque control are required.


• Two Phase Induction Motor: A.C. servomotors are typically two-phase induction motors, which are specially designed to have high dynamic response and low inertia for precise control.


• Advantages: Two-phase induction motors offer advantages such as smooth operation, high efficiency, and low maintenance requirements.


• Applications: A.C. servomotors are commonly used in robotics, CNC machines, conveyor systems, and other industrial automation applications where precise motion control is essential.

• Coefficient of Discharge: The coefficient of discharge is a dimensionless factor that represents the efficiency of a fluid flowing through an orifice or a nozzle. It is calculated as the ratio of actual discharge to theoretical discharge.


• Coefficient of Velocity: The coefficient of velocity is also a dimensionless factor that represents the velocity of a fluid jet at the vena contracta (the point where the jet is at its minimum diameter). It is calculated as the ratio of actual velocity to theoretical velocity.


• Comparison: When comparing the coefficient of velocity to the coefficient of discharge, it is observed that the coefficient of velocity is generally greater than the coefficient of discharge.


• Reasoning: This is because the coefficient of velocity takes into account only the velocity of the fluid jet, which is usually higher than the discharge rate. On the other hand, the coefficient of discharge considers various factors such as friction losses, contraction losses, and other inefficiencies in the flow, leading to a lower value compared to the coefficient of velocity.

• Capacitance in force-current analogy: Capacitance is analogous to mass in the force-current analogy.


• What is capacitance: Capacitance is a measure of an object's ability to store electric charge. It is defined as the ratio of the change in electric charge on an object to the corresponding change in electric potential.


• Analogy to mass: In the force-current analogy, capacitance is analogous to mass. This is because just as mass resists changes in velocity (inertia), capacitance resists changes in voltage (inertia in electrical terms).


• Similarities between capacitance and mass: Both capacitance and mass represent the inertia of a system. Capacitance resists changes in voltage, just as mass resists changes in velocity.


• Importance of analogy: Understanding the analogy between capacitance and mass can help in grasping the concept of capacitance better, especially for those familiar with the force-current analogy.