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Past Questions — 2026
A solar cell is basically:
A)
a voltage source, controlled by flux of radiation
B)
a current source, controlled by flux of radiation
C)
an uncontrolled current source
D)
an uncontrolled voltage source
A solar cell is commonly modeled as a current source because the photocurrent it generates is proportional to the incident solar radiation (light flux). The output current changes with radiation intensity, so it is a current source controlled by flux of radiation. Option (a) is incorrect because a solar cell is not primarily modeled as a voltage source. Options (c) and (d) are incorrect because the solar cell output is not independent of illumination.
Transformer is rated in Volt-Amps (VA) because:
A)
Ohmic loss depends on Transformer voltage
B)
heat loss is expressed in Volt-Ampere
C)
Core loss depends on Transformer Current
D)
transformer operates at high efficiency
A transformer is rated in VA (apparent power), not in watts, because its capacity is limited by both voltage and current, and its losses are nearly independent of load power factor. In practice, transformer efficiency is very high, so the real power loss is small compared to its rated apparent power. Hence the VA rating indicates the maximum voltage-current combination it can safely handle. The other options are incorrect: ohmic loss depends mainly on current, core loss depends mainly on voltage, and heat loss is not expressed in volt-amperes.
The percentage of the incoming radiation reflected back to space by the earth is:
A)
10%
B)
20%
C)
30%
D)
40%
The Earth reflects about 30% of the incoming solar radiation back to space. This is called the Earth's albedo. Hence, option (c) is correct. The other options are incorrect because 10%, 20%, and 40% do not match the commonly accepted average planetary reflectivity.
The most commonly used semiconductor in the manufacturing of a transistor is:
A)
Germanium
B)
Silicon
C)
Carbon
D)
None of the above
Silicon is the most commonly used semiconductor material for making transistors because it is abundant, inexpensive, and has better thermal stability and reliability than germanium. Germanium was used in early transistors, but silicon replaced it in most modern applications. Carbon is not used as the standard semiconductor material for transistor manufacturing.
At a slip of 4%, maximum possible speed of a 3 phase squirrel cage induction motor is:
A)
2880 rpm
B)
3000 rpm
C)
1500 rpm
D)
1440 rpm
For a 3-phase induction motor, actual speed is given by N = Ns(1 - s), where Ns is synchronous speed and s is slip. The standard synchronous speed for a 50 Hz, 2-pole motor is 3000 rpm. At 4% slip, N = 3000 × (1 - 0.04) = 3000 × 0.96 = 2880 rpm. Hence, 2880 rpm is correct. The other options are not consistent with 4% slip from 3000 rpm.
What type of current must be used to charge a DC battery?
A)
Alternating Current (AC)
B)
Direct Current (DC)
C)
Pulsating AC
D)
High-frequency AC
A DC battery must be charged with direct current because the battery stores energy in one direction of flow. Charging requires current of fixed polarity so that the chemical reaction inside the battery is reversed correctly. Alternating current would keep changing direction, so it is unsuitable unless first converted to DC. Therefore, the correct answer is Direct Current (DC).
The vertical interval (VI) of a level bench terrace is 1.5 m and the land slope is 10%. The width (W) of the bench terrace will be:
A)
10 m
B)
12 m
C)
15 m
D)
18 m
To find the width of a level bench terrace, we use the fundamental relationship between the vertical interval (VI), the land slope (S), and the horizontal width (W).
1. **Given Data:**
- Vertical Interval (VI) = 1.5 m
- Land Slope (S) = 10% = 0.10
2. **Formula:**
The vertical interval is the product of the land slope and the horizontal distance (width) between the terraces.
Formula: VI = S × W
3. **Calculation:**
Rearranging the formula to solve for W:
W = VI / S
W = 1.5 m / 0.10
W = 15 m
4. **Conclusion:**
The width of the bench terrace is 15 meters.
- Option (a) 10 m is incorrect as it would result in a VI of 1.0 m.
- Option (b) 12 m is incorrect as it would result in a VI of 1.2 m.
- Option (d) 18 m is incorrect as it would result in a VI of 1.8 m.
Silica in excess causes:
A)
The cement to set slowly
B)
The cement to set quickly
C)
The cement to expand
D)
The cement to disintegrate
In the chemical composition of Portland cement, silica (SiO2) is a primary constituent that provides strength through the formation of calcium silicate hydrates (C-S-H gel). However, the balance of ingredients is critical for the setting time. An excess of silica (SiO2) in the cement composition acts as a retarder, which slows down the hydration process and consequently causes the cement to set more slowly. Conversely, an excess of alumina (Al2O3) or iron oxide (Fe2O3) typically accelerates the setting process (causing it to set quickly). Expansion and disintegration are generally caused by excess lime (CaO) or the presence of magnesium oxide (MgO) and sulfates, not by excess silica.
Tie lines are also called:
A)
Base lines
B)
Check lines
C)
Contour lines
D)
Traverses
In surveying, specifically in chain surveying, tie lines are lines joined to locate interior details of a survey area. They are used to 'tie' the positions of objects to the main survey framework. Because these lines are used to verify the accuracy of the framework and check for errors in the measurement of the main triangles, they are also commonly referred to as 'check lines'.
Why other options are incorrect:
- a. Base lines: The base line is the longest and most important line in a survey, from which the rest of the network is built. It is a fixed reference, not a check line.
- c. Contour lines: These are imaginary lines joining points of equal elevation on a map, used for topographic mapping, not for framework verification.
- d. Traverses: A traverse is a series of connected lines whose lengths and directions are measured to determine the relative positions of points; it is a method of surveying rather than a specific type of verification line.
The moment diagram for a cantilever beam whose free end is subjected to a bending moment, will be:
A)
Parabola
B)
Triangle
C)
Rectangle
D)
Cubic parabola
To determine the shape of the bending moment diagram (BMD), we analyze the internal moment at any section of the beam.
1. **Beam Setup**: Consider a cantilever beam of length 'L' fixed at one end and free at the other. A concentrated bending moment 'M' is applied at the free end.
2. **Internal Moment Calculation**: Let 'x' be the distance from the free end. The internal bending moment at any section 'x' is the sum of the moments acting to one side of that section. In this case, the only external load is the moment 'M' applied at the end.
3. **Equation**: The bending moment M(x) at any point x along the beam is constant: M(x) = M.
4. **Geometric Interpretation**: Since the value of the bending moment is the same at every cross-section from the free end to the fixed support, the plot of the bending moment against the length of the beam is a horizontal straight line.
5. **Diagram Shape**: A constant value plotted over a length results in a rectangular area between the baseline (beam axis) and the moment value line.
Comparison with other options:
- **Parabola**: Occurs when the beam is subjected to a Uniformly Distributed Load (UDL).
- **Triangle**: Occurs when the beam is subjected to a concentrated point load at the end.
- **Cubic Parabola**: Occurs when the beam is subjected to a uniformly varying load (UVL).
For a dumpy level in perfect adjustment, the horizontal cross hair should be in a plane________.
A)
parallel to vertical axis
B)
parallel to axis of bubble tube
C)
perpendicular to vertical axis
D)
None of these
In a dumpy level, 'perfect adjustment' refers to the condition where the instrument is correctly calibrated so that the line of sight is truly horizontal when the bubble is centered. For this to occur, the following geometric relationships must hold: 1. The vertical axis must be truly vertical. 2. The line of collimation (the line passing through the cross-hairs) must be perpendicular to the vertical axis. 3. The horizontal cross-hair must be in a plane that is perpendicular to the vertical axis. If the horizontal cross-hair were not perpendicular to the vertical axis, the line of sight would tilt as the instrument is rotated, leading to errors in leveling. Therefore, the horizontal cross-hair must lie in a plane perpendicular to the vertical axis to ensure a consistent horizontal plane of sight.
The hydraulic jump is characterized by a sudden:
A)
increase in velocity
B)
increase in depth
C)
decrease in discharge
D)
increase in channel slope
A hydraulic jump occurs when a flow of liquid changes rapidly from a supercritical state (high velocity, low depth) to a subcritical state (low velocity, high depth).
1. **Mechanism**: When fast-moving water (supercritical flow) meets a slower-moving body of water or encounters an obstruction/slope change, the kinetic energy is converted into potential energy. This results in a sudden, turbulent rise in the water level.
2. **Velocity**: Because the flow transitions from supercritical to subcritical, the velocity actually decreases significantly, making option (a) incorrect.
3. **Discharge**: According to the continuity equation (Q = Area × Velocity), the total discharge remains constant throughout the jump; it does not decrease, making option (c) incorrect.
4. **Channel Slope**: While a change in slope can trigger a jump, the jump itself is a phenomenon of the flow, not a change in the physical slope of the channel, making option (d) incorrect.
Therefore, the defining physical characteristic of a hydraulic jump is the sudden increase in depth.
Spacing of check dams normally ranges from:
A)
30 to 60 m
B)
50 to 100 m
C)
150 to 200 m
D)
200 to 250 m
Check dams are small, temporary or permanent structures constructed across a swale, drainage ditch, or intermittent stream to reduce water velocity, prevent soil erosion, and encourage groundwater recharge. The spacing between check dams is determined by the slope of the terrain and the desired ponding depth. In standard hydraulic and soil conservation engineering practices, the spacing is typically designed such that the toe of the pond created by one dam is just above the crest of the next dam to prevent scouring. For typical slopes found in hilly or agricultural terrains where check dams are most common, the standard spacing normally ranges from 50 to 100 meters. Option (a) is generally too close for standard check dams (more typical of very steep gully plugs), while options (c) and (d) are too far apart to effectively control velocity and prevent erosion in most runoff-prone areas.
Fuller’s rule is primarily used to determine the:
A)
optimum water cement ratio for maximum strength
B)
ideal grading of aggregates to achieve maximum density
C)
setting time of cement paste in concrete
D)
proportion of fine aggregate in mortar
Fuller's Rule (also known as the Fuller-Thompson curve) is a mathematical formula used in concrete technology to determine the optimal particle size distribution (grading) of aggregates. The primary objective of this rule is to achieve the maximum packing density of the aggregate skeleton. By filling the voids between larger particles with smaller particles, the amount of cement paste required to fill the remaining gaps is minimized, which leads to increased strength, reduced shrinkage, and better economy.
Analysis of other options:
- Option (a) is incorrect because the water-cement ratio is governed by the Abrams' Law, not Fuller's rule.
- Option (c) is incorrect because setting time is determined by chemical reactions and tested using the Vicat apparatus.
- Option (d) is incorrect because the proportion of fine aggregate is typically determined by mix design methods (like IS code or ACI methods) based on the volume of coarse aggregates, not specifically by Fuller's rule alone.
Scale is defined as:
A)
The fixed ratio that every distance on the plan bears with corresponding distance on the ground.
B)
The fixed ratio that every distance on the ground bears with corresponding distance on the plan
C)
The difference between the distance on the plan to the actual distance on the ground.
D)
The measurement of distance on the ground.
In surveying and cartography, 'Scale' is defined as the ratio of a distance on a map or plan to the corresponding actual distance on the ground. Mathematically, it is expressed as: Scale = (Distance on Map) / (Distance on Ground).
- Option (a) is correct because it accurately describes this ratio (Map Distance : Ground Distance).
- Option (b) is incorrect because it describes the inverse of the scale (Ground Distance : Map Distance), which is known as the 'Scale Factor' or simply the reciprocal of the scale.
- Option (c) is incorrect because scale is a ratio (division), not a difference (subtraction).
- Option (d) is incorrect because the measurement of distance on the ground is simply 'ground distance' or 'actual distance', not the scale.
Kirpich formula estimates the time of concentration (Tc) as:
A)
T = 0.02((L3 / H)1/2 )0.77
B)
T = 0.02L0.77 S -0.385
C)
Tc = 0.02(LS) -0.385
D)
Tc = 0.02(LS)0.77
The Kirpich formula is a widely used empirical equation in hydrology to estimate the Time of Concentration (Tc), which is the time required for water to travel from the hydraulically most distant point of a watershed to the outlet. The standard form of the Kirpich equation is: Tc = 0.0195 * L^0.77 * S^-0.385, where Tc is the time of concentration in hours, L is the length of the main channel in miles, and S is the average slope of the channel in ft/mile. In many textbooks and exam contexts, the coefficient 0.0195 is rounded to 0.02. Therefore, the formula is expressed as Tc = 0.02 * L^0.77 * S^(-0.385).
Analyzing the options:
- Option (a) is mathematically incorrect and does not follow the Kirpich derivation.
- Option (b) matches the standard empirical form: T = 0.02 * L^0.77 * S^(-0.385).
- Option (c) and (d) incorrectly group L and S together inside the parentheses, which changes the mathematical relationship (the exponents must apply to L and S independently).
There are 25 girls in a row. Hannah was shifted by three places towards her right side and she occupies the middle position in the row. What was her original position from the left end?
A)
15th
B)
16th
C)
12th
D)
10th
Option A is correct: 15th.
The velocity-area method of measuring flow in a river involves:
A)
Dividing the stream into sections, measuring area and velocity for each, and summing the discharge.
B)
Measuring the total volume of the river.
C)
Using a tracer to measure the concentration.
D)
Measuring only the maximum velocity.
The velocity-area method is a fundamental technique in hydraulics used to determine the discharge (Q) of an open channel or river. The basic formula is Q = A × V, where A is the cross-sectional area and V is the average velocity. Because velocity varies across the width and depth of a river (due to friction at the banks and bed), the stream is divided into several vertical sections (sub-areas). For each section, the area is calculated and the velocity is measured (typically using a current meter). The total discharge is then the sum of the discharges of all individual sections: Q = Σ (ai × vi).
Why other options are incorrect:
- Option b: Measuring total volume is impractical for a flowing river and describes a static volume, not a flow rate (discharge).
- Option c: Using a tracer describes the 'Dilution Method' or 'Chemical Method', not the velocity-area method.
- Option d: Measuring only the maximum velocity would lead to a significant overestimation of the total flow, as velocity is not uniform across the section.
In which condition of Froude number, a strong hydraulic jump takes place:
A)
F 9.0
B)
F 7.0
C)
F = 4.5 – 9.0
D)
F = 1.7 – 2.5
A hydraulic jump is a phenomenon where a supercritical flow transforms into a subcritical flow, resulting in a significant loss of energy. The nature and classification of the jump depend on the upstream Froude number (Fr). According to the standard classification of hydraulic jumps (often attributed to USBR - United States Bureau of Reclamation):
1. Undular Jump: 1.0 < Fr < 1.7
2. Weak Jump: 1.7 < Fr < 2.5
3. Oscillating Jump: 2.5 < Fr < 4.5
4. Steady Jump: 4.5 < Fr < 9.0
5. Strong Jump: Fr > 9.0
In a 'Strong Jump', the turbulence is very high, and the energy dissipation is significant. Therefore, a strong hydraulic jump takes place when the Froude number is greater than or equal to 9.0.
Analysis of options:
- Option (a) F 9.0: Correct, this defines a Strong Jump.
- Option (b) F 7.0: Incorrect, as the range 4.5 to 9.0 is categorized as a Steady Jump.
- Option (c) F = 4.5 – 9.0: Incorrect, this is a Steady Jump.
- Option (d) F = 1.7 – 2.5: Incorrect, this is a Weak Jump.
For accurate weir measurement, the nappe should be:
A)
Aerated and free
B)
Clinging
C)
Submerged
D)
Turbulent
In hydraulic structures, a weir is used to measure the flow rate of water in an open channel. The 'nappe' is the sheet of water that flows over the crest of the weir. For the standard discharge equations (like the Francis formula) to be accurate, the nappe must be 'free' and 'aerated'.
1. **Free Nappe**: This means the water falls freely from the crest without being obstructed or pushed back by downstream water (which would cause 'submergence').
2. **Aerated Nappe**: Air must be allowed to circulate under the nappe. If air is not present, a partial vacuum forms between the nappe and the weir face, which sucks the nappe downward (causing it to 'cling'). This vacuum changes the flow characteristics and leads to an inaccurate (higher) reading of the head over the weir, thereby introducing errors in the discharge calculation.
Why other options are incorrect:
- **Clinging (b)**: A clinging nappe occurs when air is not supplied under the nappe, leading to inaccurate measurements due to the vacuum effect.
- **Submerged (c)**: A submerged nappe occurs when the downstream water level rises above the crest, reducing the flow rate for a given head and requiring a correction factor.
- **Turbulent (d)**: Turbulence in the approach flow or the nappe itself introduces instability and measurement errors.
One hectare is equal to:
A)
1,000 m²
B)
10,000 m²
C)
100,000 m²
D)
1 km²
A hectare (symbol: ha) is a non-SI metric unit of area used primarily for measuring land. By definition, one hectare is equal to the area of a square with sides of 100 meters.
Calculation:
Area = Length × Width
Area = 100 m × 100 m = 10,000 m².
Analysis of other options:
- Option (a) 1,000 m² is only one-tenth of a hectare.
- Option (c) 100,000 m² is equal to 10 hectares.
- Option (d) 1 km² is equal to 1,000 m × 1,000 m = 1,000,000 m², which is equal to 100 hectares.
Centrifugal pumps are used for pumping water when:
A)
Both head and discharge are high
B)
Discharge is high and head is low
C)
Both discharge and head are low
D)
Discharge is low and head is high
Centrifugal pumps are kinetic energy pumps that convert rotational energy from an impeller into hydrodynamic energy of the fluid. Their operational characteristics are defined by their performance curves: they are designed to handle large volumes of liquid (high discharge) but are limited in the amount of pressure or height (head) they can generate compared to positive displacement pumps.
1. Why Option (b) is correct: Centrifugal pumps are most efficient when moving a high volume of water against a relatively low to medium head. This makes them ideal for applications like irrigation, water supply, and drainage.
2. Why Option (a) is incorrect: For both high head and high discharge, multiple centrifugal pumps are often placed in series and parallel, or specialized high-pressure pumps are used, as a single standard centrifugal pump cannot efficiently achieve both extremes.
3. Why Option (c) is incorrect: While they can operate at low head and discharge, this is not the primary reason or the optimal condition for which they are specifically 'used' or selected over other pump types.
4. Why Option (d) is incorrect: For low discharge and high head, positive displacement pumps (like reciprocating pumps) are used because centrifugal pumps would require an impractical number of stages to reach very high heads while maintaining low flow.
A Parshall flume consists of three main components. Which of the following is NOT one of them?
A)
Converging section
B)
Filtering section
C)
Throat section
D)
Diverging section
A Parshall flume is a specially shaped open channel used for measuring the flow rate of water or wastewater. It is designed to create a critical flow condition, allowing the discharge to be calculated based on a single head measurement. It consists of three distinct geometric components:
1. Converging section: The inlet part where the channel narrows, accelerating the flow.
2. Throat section: The narrowest part of the flume where the flow reaches critical depth.
3. Diverging section: The outlet part where the channel widens to slow the flow and recover some of the energy loss.
A 'Filtering section' is not a component of a Parshall flume; filtering is a separate water treatment process and is not part of the hydraulic geometry used for flow measurement in a flume.
The level at which the water stands in a well before pumping starts is called:
A)
Piezometric surface
B)
Pumping water level
C)
Initial water level
D)
Static water level
In groundwater hydrology, the 'Static Water Level' (SWL) is defined as the level of water in a well when the water is in equilibrium with the surrounding aquifer, specifically before any pumping begins or after the water level has recovered following a pumping period.
Here is why the other options are incorrect:
- a. Piezometric surface: This refers to the imaginary surface to which water would rise in a piezometer; while the static water level in a well reflects the piezometric surface of the aquifer, the specific term for the level inside the well is the static water level.
- b. Pumping water level: This is the level to which the water drops during the actual process of pumping (also known as the dynamic water level).
- c. Initial water level: While descriptive, this is not the standard technical term used in hydrology and engineering textbooks.
Therefore, the correct technical term for the water level before pumping starts is the Static Water Level.
Which term is used for the surface to which elevations are referred?
A)
Benchmark
B)
Level line
C)
Horizontal plane
D)
Datum
In surveying, a 'Datum' is defined as any arbitrary surface (usually a horizontal plane or a curved surface like the Mean Sea Level) to which all elevations are referred. The vertical distance of a point above or below this datum is called its elevation or reduced level (RL).
Why other options are incorrect:
- a. Benchmark: A benchmark is a fixed reference point of known elevation. While it is used to start leveling, it is a point on the ground, not the reference surface itself.
- b. Level line: A level line is a line that is everywhere perpendicular to the direction of gravity; it is a line, not a reference surface.
- c. Horizontal plane: While a datum can be a horizontal plane, 'Datum' is the specific technical term used in surveying to describe the reference surface for elevations.