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Past Questions
The unit weight per running meter of 12 mm dia. steel bar is:-
A)
0.89 kg
B)
0.62 kg
C)
0.78 kg
D)
0.65 kg
To calculate the unit weight of a steel bar per running meter, we use the standard formula derived from the volume of a cylinder and the density of steel.
1. **Formula**: The weight of a steel bar is given by:
Weight (W) = Volume × Density
W = (π/4 × d² × L) × ρ
Where:
- d = diameter of the bar (in meters)
- L = length of the bar (1 meter for unit weight)
- ρ = density of steel (standard value is 7850 kg/m³)
2. **Simplified Formula**: For steel bars, the formula is commonly simplified to:
W = (d² / 162.2) kg/m
(where d is in millimeters)
3. **Calculation for 12 mm bar**:
W = (12)² / 162.2
W = 144 / 162.2
W ≈ 0.8877 kg/m
4. **Rounding**: Rounding to two decimal places, we get 0.89 kg/m.
Comparing this result with the given options:
- Option (a) 0.89 kg matches our calculation.
- Option (b) 0.62 kg corresponds to a 10 mm bar (10²/162.2 ≈ 0.617).
- Option (c) 0.78 kg is incorrect.
- Option (d) 0.65 kg is incorrect.
The term “Gross Head” in a Small Hydel Project refers to:-
A)
The difference in water level between the forebay and the tailrace
B)
The pressure of water at the turbine inlet
C)
The height of the dam
D)
The total capacity of the reservoir
In hydroelectric power terminology, 'Head' refers to the vertical distance water falls to drive a turbine.
1. **Gross Head**: This is the total vertical distance between the water surface at the intake (or forebay) and the water surface at the discharge point (tailrace). It represents the maximum potential energy available per unit weight of water.
2. **Net Head**: This is the actual head available at the turbine inlet after subtracting losses due to friction in the penstock, bends, and valves from the Gross Head (Net Head = Gross Head - Head Losses).
Evaluating the options:
- **Option a** is correct as it defines the total vertical drop from the source (forebay) to the exit (tailrace).
- **Option b** describes the 'Net Head' or the actual pressure head at the turbine.
- **Option c** is incorrect because the height of the dam is a structural dimension and does not necessarily equal the hydraulic head (which depends on water levels).
- **Option d** refers to the volume of water storage, not the hydraulic head.
The difference in height of the water level between the level in storage and tailrace is called:-
A)
Net head
B)
Gross head
C)
Rated head
D)
Design head
In hydroelectric power plants, the 'head' refers to the vertical distance the water falls to drive the turbine.
1. **Gross Head (Option b):** This is the total vertical difference in elevation between the water surface at the intake (storage reservoir) and the water surface at the tailrace (the point where water exits the plant). It represents the maximum potential energy available per unit weight of water.
2. **Net Head (Option a):** This is the actual head available at the turbine inlet. It is calculated as the Gross Head minus the losses due to friction in the penstock, bends, and valves (Net Head = Gross Head - Head Losses).
3. **Rated Head (Option c):** This is the head at which the turbine is designed to operate to produce its rated output power.
4. **Design Head (Option d):** This is the specific head for which the turbine is optimized for maximum efficiency during the design phase.
Since the question specifically asks for the difference in height between the storage level and the tailrace level, it is referring to the total potential difference, which is the Gross Head.
A first class brick when immersed in cold water for 24 hours should not absorb water more than:-
A)
15%
B)
20%
C)
22%
D)
25%
According to the Indian Standard (IS) specifications for bricks, the water absorption test is used to determine the quality and porosity of the brick. For a first-class brick, the maximum permissible water absorption after being immersed in cold water for 24 hours is 20% of its dry weight.
Breakdown of standards:
- First Class Bricks: Water absorption should not exceed 20% of dry weight.
- Second Class Bricks: Water absorption should not exceed 22% of dry weight.
- Third Class Bricks: Water absorption may be higher, typically around 25% or more depending on the specific local standard.
Therefore, option (b) is the correct technical requirement for a first-class brick.
In geodetic surveys, higher accuracy is achieved, if:-
A)
Curvature of the earth surface is ignored
B)
Curvature of the earth surface is taken into account
C)
Angles between the curved lines are treated as plane angles
D)
Satellite signal is taken into account
Surveying is broadly divided into two categories: Plane Surveying and Geodetic Surveying.
1. Plane Surveying: In this type of survey, the earth's surface is assumed to be a flat plane. The curvature of the earth is ignored. This is acceptable for small areas (typically less than 250 sq km) because the error introduced is negligible.
2. Geodetic Surveying: This is used for very large areas or high-precision work. Because the earth is an oblate spheroid, the curvature of the surface becomes significant over long distances. To achieve higher accuracy, the curvature of the earth must be taken into account using spherical trigonometry and ellipsoidal calculations.
Analysis of options:
- Option (a) is incorrect because ignoring curvature leads to 'plane surveying', which is less accurate for large areas.
- Option (b) is correct because accounting for the earth's curvature is the defining characteristic of geodetic surveying to ensure high precision.
- Option (c) is incorrect because treating curved lines as plane angles is a simplification used in plane surveying, not geodetic surveying.
- Option (d) is incorrect because while satellites (GPS/GNSS) are tools used in modern geodetic surveys, the fundamental principle that enables the 'higher accuracy' of the geodetic method itself is the mathematical consideration of the earth's curvature.
A key consideration when selecting a site for a Small Hydel Project is:-
A)
Distance from major cities
B)
Availability of suitable land for construction of weir
C)
Proximity to existing transmission lines
D)
Availability of skilled labor
In the selection of a site for a Small Hydel Project (SHP), the primary technical requirement is the ability to divert or store water efficiently to create the necessary head and flow. The construction of a weir (or diversion dam) is fundamental to this process as it ensures a steady supply of water into the intake structure. Therefore, the availability of suitable land—specifically land with stable geological foundations and appropriate topography to support a weir—is a critical technical consideration.
Why other options are incorrect:
- Option (a) Distance from major cities: While urban proximity affects demand, it is not a primary technical site selection criterion for the project's viability.
- Option (c) Proximity to existing transmission lines: This is an economic consideration to reduce costs, but it is secondary to the physical possibility of harnessing water (the weir).
- Option (d) Availability of skilled labor: Labor can be transported to a site; it does not dictate whether a specific geographical location is suitable for a hydroelectric project.
The primary function of a trash rack in a Small Hydel Project is to:-
A)
Regulate water flow
B)
Prevent debris from entering the turbine
C)
Increase water pressure
D)
Generate electricity
A trash rack is a screen made of metal bars installed at the intake of a hydroelectric project (including Small Hydel Projects). Its primary purpose is to act as a filter that prevents floating debris—such as logs, leaves, plastic, and other foreign objects—from entering the penstock and reaching the turbine. If debris enters the turbine, it can cause severe mechanical damage to the runner blades, clog the system, or cause imbalances that lead to turbine failure.
Analysis of other options:
- Option (a) Regulate water flow: This is the function of the intake gate or the governor valve, not the trash rack.
- Option (c) Increase water pressure: Water pressure is increased by the head (height difference) and the design of the penstock; a trash rack actually causes a slight pressure drop (head loss) due to friction.
- Option (d) Generate electricity: Electricity is generated by the turbine and the generator set, not by the intake screening system.
The bond strength of concrete increases with:-
A)
The quality of steel
B)
The tensile strength of the steel
C)
The grade of concrete
D)
The quality of sand
Bond strength in reinforced concrete refers to the capacity of the concrete to grip the reinforcing steel bar, preventing slippage. This bond is primarily achieved through chemical adhesion, friction, and mechanical interlocking (in the case of deformed bars).
1. Why 'The grade of concrete' is correct: The grade of concrete is a measure of its compressive strength. As the grade of concrete increases (e.g., from M20 to M40), the density and the strength of the cement paste matrix increase. This results in a stronger grip (higher adhesion and higher bearing pressure on the ribs of deformed bars) around the steel reinforcement, thereby increasing the overall bond strength.
2. Why other options are incorrect:
- (a) The quality of steel: While the surface condition (like ribs) matters, 'quality' is a general term. High-quality steel doesn't inherently increase the bond unless it refers specifically to the deformation pattern.
- (b) The tensile strength of the steel: Tensile strength is an internal property of the steel (its ability to resist pulling forces). It does not affect how the concrete grips the outside of the bar.
- (d) The quality of sand: While the grading of sand affects the workability and density of concrete, it is the overall grade (strength) of the hardened concrete that is the primary driver of bond strength.
The opened or closed conduits that carry water to the turbines is:-
A)
Power channel
B)
Penstock
C)
Desilting Tank
D)
Forebay
In a hydroelectric power plant, the penstock is the pressurized pipe or conduit that conveys water from the forebay or reservoir directly to the turbine. It is designed to handle high pressure and is typically closed (piped) to maintain the head of water.
Analysis of other options:
- a. Power channel: This is a general term, but the specific conduit leading to the turbine is the penstock.
- c. Desilting Tank: This is a basin used to remove silt and sediment from the water before it enters the conveyance system to prevent erosion of the turbine blades.
- d. Forebay: This is a holding basin or reservoir located at the end of the headrace canal, acting as a transition point before the water enters the penstock.
The amount of electrical energy that can be generated at Small Hydel Project depends upon:-
A)
Head of water
B)
Quantity of water
C)
Efficiency of Alternator
D)
Diameter of Penstock
To determine the electrical energy generated by a Small Hydel Project, we look at the fundamental power equation for hydroelectricity: P = η × ρ × g × Q × H.
1. P = Power (Watts)
2. η = Overall efficiency (including turbine and alternator)
3. ρ = Density of water
4. g = Acceleration due to gravity
5. Q = Discharge or Quantity of water (m³/s)
6. H = Net Head (m)
Electrical Energy (E) is the integral of Power over time (E = P × t). Therefore, the energy generated depends on the Head (H), the Quantity of water (Q), and the Efficiency (η).
However, in the context of competitive exams for Small Hydel Projects (SHP), the 'Quantity of water' (discharge) is often the most critical limiting factor and the primary variable that determines the total energy potential over a given period (annual energy generation), as the head is usually a fixed geographical constant for a specific site.
While options (a), (b), and (c) all mathematically influence the power, the question asks what the energy 'depends upon'. In many standard engineering textbooks for SHP, the availability of the 'Quantity of water' (flow rate) is the primary determinant of the project's capacity and energy output.
Note: If this were a 'select all that apply' question, a, b, and c would be correct. In a single-choice format, 'Quantity of water' is the most fundamental resource requirement for energy generation.
The standard thickness of ceiling plaster is:-
A)
6 mm
B)
10 mm
C)
12 mm
D)
15 mm
In building construction and plastering standards (as per IS codes and general engineering practice), the thickness of plaster varies depending on the surface being treated. For ceilings, the standard thickness of plaster is typically 12 mm. This thickness is chosen to provide a smooth, level finish to the concrete slab or beams while ensuring the plaster has sufficient bond strength to resist peeling or sagging due to gravity.
Comparison with other options:
- 6 mm: This is generally too thin for a standard ceiling coat and is more common for thin skim coats or specific internal finishes.
- 10 mm: While used in some specific regional practices, it is not the standard engineering benchmark for ceiling plaster.
- 15 mm: This thickness is more common for internal wall plastering (usually 12-15 mm) or external plastering (which can be 18-20 mm), but is considered excessive for ceilings as it increases the dead load and the risk of debonding.
The maximum power which can be developed by generators at normal head with full flow is:-
A)
Load factor
B)
Installed capacity
C)
Peak load
D)
Average load
In hydroelectric power plants, the 'Installed Capacity' refers to the maximum theoretical power that the generators can produce when operating under design conditions—specifically, at the normal operating head (the vertical distance the water falls) and with the full design flow rate of water passing through the turbines.
Here is why the other options are incorrect:
- a. Load factor: This is the ratio of the average load over a given period to the peak load during that period. It is a dimensionless ratio, not a measure of power capacity.
- c. Peak load: This is the maximum electrical demand placed on the system by consumers at a specific point in time. While it may coincide with installed capacity, it is a demand metric, not a generator capability metric.
- d. Average load: This is the mean power demand over a specific period, which is always less than or equal to the peak load and installed capacity.
The “Head” in a Small Hydel Project is:-
A)
The depth of the river
B)
The depth of the reservoir
C)
The difference in elevation between the water surface at the intake and the turbine
D)
The length of the penstock
In hydroelectric power generation, 'Head' refers to the vertical distance that water falls from the intake point to the turbine. This elevation difference creates the potential energy that is converted into kinetic energy as water flows down the penstock, and finally into mechanical energy by the turbine.
- Option (a) is incorrect because the depth of the river does not determine the energy potential available for power generation.
- Option (b) is incorrect because while the reservoir depth contributes to the total head, the 'Head' is specifically the difference between the intake level and the turbine level, not just the depth of the pool.
- Option (d) is incorrect because the length of the penstock refers to the distance the water travels, which affects friction losses (head loss), but it is not the definition of the 'Head' itself.
First class timber has an average life of:-
A)
More than 10 years
B)
5 to 10 years
C)
Less than one year
D)
1 to 5 years
In the classification of timber based on durability (resistance to decay and insect attack), timber is generally categorized into classes. First-class timber is characterized by high durability, meaning it is highly resistant to decay and can withstand environmental exposure for a prolonged period. According to standard engineering and forestry classifications for building materials, first-class timber is expected to have a service life of more than 10 years (often extending to several decades depending on the species and treatment). Options b, c, and d represent durations typical of lower-grade, non-durable, or perishable timbers that are susceptible to rapid decay.
Main ingredient in the cement composition is:-
A)
Silica
B)
Lime
C)
Clay
D)
Alumina
Portland cement is manufactured by burning a mixture of calcareous (lime-bearing) and argillaceous (clay-bearing) materials. The chemical composition of cement consists of several oxides, with Lime (CaO) being the primary constituent.
1. Lime (CaO): This is the main ingredient, typically making up about 60% to 67% of the cement. It provides strength and soundness.
2. Silica (SiO2): The second most abundant ingredient (approx. 17% to 25%), which contributes to the strength of the cement over time.
3. Alumina (Al2O3): Present in smaller quantities (approx. 3% to 8%), it acts as a flux to lower the clinkering temperature.
4. Iron Oxide (Fe2O3): Present in small amounts (approx. 0.5% to 6%), giving cement its characteristic grey color.
Since Lime has the highest percentage by weight in the composition of cement, it is the main ingredient.
When a vehicle traces a horizontal curve, it is subjected to centrifugal force in a direction of:-
A)
Inward
B)
Outward
C)
Forward
D)
Upward
When a vehicle moves along a horizontal curve, it undergoes circular motion. According to the laws of physics, any object moving in a curved path experiences a 'centrifugal force'. This is an apparent force (inertial force) that acts in the direction opposite to the centripetal force. While the centripetal force (provided by friction and superelevation) acts inward toward the center of the curve to keep the vehicle on track, the centrifugal force acts radially outward, away from the center of the curve.
- Option (a) Inward: This is the direction of the centripetal force, not the centrifugal force.
- Option (c) Forward: This is the direction of the vehicle's velocity/momentum, not the radial force.
- Option (d) Upward: This is the direction opposite to gravity and does not relate to the horizontal curvature of the path.
Small Hydel Projects are generally considered as:-
A)
Renewable and sustainable
B)
High maintenance
C)
Environmentally damaging
D)
Expensive to operate
Step-by-step reasoning:
1. Definition: Small Hydel Projects (SHPs) are hydroelectric power plants that typically generate a small amount of electricity (usually up to 25 MW, though definitions vary by region).
2. Renewable Nature: They utilize the natural flow of water (the water cycle), which is naturally replenished by rainfall, making them a 'renewable' energy source.
3. Sustainability: Unlike large-scale dams, SHPs often use 'run-of-the-river' technology, which requires little to no reservoir storage. This minimizes the displacement of people and the flooding of forests, making them 'sustainable' and environmentally friendly.
4. Analysis of other options:
- Option (b) 'High maintenance': SHPs are generally designed for simplicity and lower maintenance compared to massive industrial power plants.
- Option (c) 'Environmentally damaging': While any construction has some impact, SHPs are specifically praised for having a significantly lower environmental footprint than large hydro projects.
- Option (d) 'Expensive to operate': Once the initial capital investment is made, the operational cost of hydropower is among the lowest of all energy sources because the 'fuel' (water) is free.
Calculate the hydraulic radius for a channel having a cross-sectional area of 20 m2 and a wetted perimeter of 50 m.
A)
0.4 m
B)
0.8 m
C)
2.5 m
D)
0.6 m
The hydraulic radius (R) of a channel is defined as the ratio of the cross-sectional area of the flow (A) to the wetted perimeter (P).
Given data:
- Cross-sectional area (A) = 20 m²
- Wetted perimeter (P) = 50 m
Formula:
Hydraulic Radius (R) = Area (A) / Wetted Perimeter (P)
Calculation:
R = 20 m² / 50 m
R = 2 / 5 m
R = 0.4 m
Therefore, the hydraulic radius is 0.4 m.
- Option b (0.8 m) is incorrect as it would require a perimeter of 25 m.
- Option c (2.5 m) is incorrect as it is the result of P/A instead of A/P.
- Option d (0.6 m) is mathematically incorrect based on the given values.
At which point in the entire canal system the duty of water will be more?
A)
Head of the Minor
B)
Head of the Distributary
C)
Head of the Water-course
D)
Head of the Branch
Duty of water is defined as the area of land that can be irrigated by a constant supply of 1 cumec of water throughout the base period. In a canal system, water is lost due to seepage and evaporation as it travels from the main canal to the field.
1. Hierarchy of the system: Main Canal $\rightarrow$ Branch Canal $\rightarrow$ Distributary $\rightarrow$ Minor $\rightarrow$ Water-course (Field Channel).
2. Conveyance Losses: As water moves from the head of the branch toward the field, a significant portion is lost to seepage. To deliver 1 unit of water to the field, more than 1 unit must be released at the head of the branch.
3. Relationship with Duty: Duty is inversely proportional to the amount of water required per unit area. Since the most water is 'lost' before reaching the water-course, the water that actually reaches the 'Head of the Water-course' is the most 'efficient' in terms of the area it serves relative to the volume delivered at that specific point.
4. In simpler terms: The duty is lowest at the head of the main canal/branch (because it must account for all downstream losses) and increases as we move downstream. Therefore, the duty is maximum at the point closest to the field, which is the Head of the Water-course.
Alumina in excess causes _________.
A)
Reduces the strength of the cement
B)
Increases the strength of the cement
C)
No change
D)
Sometimes increase or decrease the strength of the cement
In the chemical composition of Portland cement, Alumina (Al2O3) acts as a flux, lowering the clinkering temperature. However, its quantity must be carefully controlled. While a moderate amount is necessary for the formation of aluminate phases, an excess of alumina leads to the formation of more C3A (Tricalcium Aluminate). While C3A contributes to early strength, an overall excess of alumina generally reduces the ultimate strength of the cement and increases the heat of hydration, which can lead to cracking. Furthermore, high alumina content makes the cement more susceptible to sulfate attack. Therefore, in the context of overall structural integrity and long-term strength, excess alumina is detrimental.
Concrete placed in cold weather will take __________ time to gain strength.
A)
No
B)
Less
C)
More
D)
Equal to hot weather
The hardening of concrete is a chemical process called hydration, where cement reacts with water to form calcium silicate hydrate (C-S-H) gel, which provides strength. This chemical reaction is temperature-dependent. According to the Arrhenius equation, the rate of chemical reactions decreases as temperature decreases. In cold weather, the rate of hydration slows down significantly, meaning the concrete takes a longer period to reach its design strength compared to concrete cured at standard or warm temperatures. If the temperature drops below freezing, the hydration process can stop entirely or the water in the concrete can freeze, causing internal damage (spalling). Therefore, concrete placed in cold weather requires 'more' time to gain strength.
With what type of mounting does a sprinkler irrigation network give the best results?
A)
Nozzles
B)
Open Pipes
C)
Pipes with holes near the crop
D)
Revolving Sprinkler Heads
Sprinkler irrigation is designed to simulate natural rainfall. To achieve the 'best results'—which in irrigation engineering means achieving a uniform distribution of water over a wide area with minimal labor—the system requires a mechanism that can distribute water in a circular or semi-circular pattern.
1. **Revolving Sprinkler Heads (Correct):** These use the pressure of the water to rotate the nozzle, ensuring that water is spread evenly across the field. This prevents over-watering in one spot (which causes runoff/leaching) and under-watering in others, maximizing water-use efficiency.
2. **Nozzles (Incorrect):** While a sprinkler head contains a nozzle, a stationary nozzle alone would only water a small, concentrated area, leading to poor uniformity.
3. **Open Pipes (Incorrect):** This would result in uncontrolled flooding or surface irrigation, not sprinkler irrigation.
4. **Pipes with holes near the crop (Incorrect):** This describes a primitive form of drip or subsurface irrigation, not a sprinkler system, and is highly inefficient due to clogging and uneven pressure distribution.
Which is not a form of precipitation?
A)
Water vapour
B)
Hail
C)
Drizzle
D)
Snow
Precipitation is defined as any product of the condensation of atmospheric water vapour that falls under gravity from clouds.
1. **Water vapour (Option a):** This is water in its gaseous state. It exists in the atmosphere but is not 'falling' as a product of condensation; rather, it is the source material that must condense or freeze to become precipitation. Therefore, it is not a form of precipitation.
2. **Hail (Option b):** This is a form of solid precipitation consisting of balls or lumps of ice.
3. **Drizzle (Option c):** This is a form of liquid precipitation consisting of very small water droplets (smaller than 0.5 mm).
4. **Snow (Option d):** This is a form of solid precipitation consisting of ice crystals.
Since hail, drizzle, and snow are all forms of water falling from the atmosphere to the earth's surface, water vapour is the correct answer as it is the only option that is not a form of precipitation.
Which irrigation method is best suited for orchards and vineyards?
A)
Flood irrigation
B)
Sprinkler irrigation
C)
Drip irrigation
D)
Check flooding
Step-by-step reasoning:
1. Analysis of Crop Type: Orchards (fruit trees) and vineyards (grapes) are characterized by wide spacing between plants. They have localized root zones rather than a continuous carpet of vegetation.
2. Evaluation of Drip Irrigation: Drip irrigation (also known as trickle irrigation) delivers water slowly and precisely to the root zone of each individual plant. This minimizes water waste, reduces weed growth between rows, and prevents the foliage from getting wet, which reduces the risk of fungal diseases common in vineyards.
3. Evaluation of Flood/Check Flooding: Flood and check flooding (Options a and d) apply water to the entire surface area. For orchards, this is highly inefficient as it wastes water on the empty spaces between trees and can lead to waterlogging or root rot.
4. Evaluation of Sprinkler Irrigation: While better than flooding, sprinkler irrigation (Option b) applies water to the entire area and the foliage. In vineyards and orchards, wetting the leaves can promote mildew and other diseases, and it is less water-efficient than drip irrigation for widely spaced crops.
Conclusion: Drip irrigation is the most efficient and technically suited method for high-value, widely spaced perennial crops like those found in orchards and vineyards.
What is the most accurate method of estimation from the following?
A)
Building cost index estimate
B)
Detailed estimate
C)
Plinth area estimate
D)
Cube rate estimate
In civil engineering estimation and costing, estimates are categorized based on their level of accuracy and the stage of the project.
1. **Detailed Estimate (Option b):** This is the most accurate method because it involves the preparation of a complete set of drawings and a detailed 'Bill of Quantities' (BOQ). Every single item of work (excavation, concrete, masonry, finishing, etc.) is measured accurately from the drawings and multiplied by the current schedule of rates. It provides the most precise cost projection.
2. **Plinth Area Estimate (Option c):** This is an approximate or preliminary estimate. It is calculated by multiplying the plinth area of the building by a prevailing plinth area rate. It is used for initial budgeting but lacks precision as it ignores specific structural requirements.
3. **Cube Rate Estimate (Option d):** This is also an approximate estimate, more accurate than the plinth area method because it considers the volume (height) of the building, but it is still far less accurate than a detailed estimate.
4. **Building Cost Index Estimate (Option a):** This is a method used to adjust previous costs to current values based on inflation or market indices. It is a tool for updating estimates rather than a primary method of detailed quantification.
Therefore, the Detailed Estimate is the most accurate as it is based on actual quantities of materials and labor required for the specific project.