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Tamil Nadu HSE Second Year Basic Civil Engineering study materials
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Tamil Nadu HSE Second Year Basic Civil Engineering practice questions

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Question 1Building Materials and Construction

In a standard modular brick used in Indian construction, the nominal size including the mortar joint is:

  1. 230 mm × 110 mm × 70 mm
  2. 200 mm × 100 mm × 100 mm Correct answer.
  3. 190 mm × 90 mm × 90 mm
  4. 230 mm × 110 mm × 110 mm

Explanation

The modular brick has actual dimensions of 190 mm × 90 mm × 90 mm, and adding a 10 mm mortar joint on each face gives a nominal size of 200 mm × 100 mm × 100 mm. The nominal size is what is used for planning wall lengths and openings so that bricks plus joints add up to neat modular multiples.

Question 2Building Materials and Construction

A first-class brick, when struck with another brick or with a hammer, should produce:

  1. A ringing sound only when wet
  2. A clear metallic ringing sound Correct answer.
  3. A muffled sound with powder falling off
  4. A dull thud with crumbling edges

Explanation

A well-burnt, dense brick gives a clear metallic ringing sound when struck, showing good vitrification and freedom from cracks. A dull or muffled sound indicates under-burning, internal cracks, or excess porosity, all of which reduce strength and durability.

Question 3Building Materials and Construction

Lime used for making mortar is generally slaked before use mainly because slaking:

  1. Improves the colour of the finished plaster
  2. Converts quicklime into a workable plastic putty and removes the danger of later expansion Correct answer.
  3. Reduces the setting time of the cement
  4. Increases the clay content of the lime

Explanation

Slaking is the controlled addition of water to quicklime, converting calcium oxide into calcium hydroxide. This produces a plastic putty that can be mixed with sand, and it ensures that any residual expansion takes place before the lime is placed in the wall rather than after.

Question 4Building Materials and Construction

Which constituent of ordinary Portland cement is responsible for the early gain of strength, especially within the first 7 to 28 days?

  1. Dicalcium silicate (C2S)
  2. Tricalcium silicate (C3S) Correct answer.
  3. Tetracalcium aluminoferrite (C4AF)
  4. Tricalcium aluminate (C3A)

Explanation

Tricalcium silicate hydrates rapidly and is the main contributor to early strength development in the first four weeks. Dicalcium silicate hydrates slowly and contributes mainly to strength gain at later ages, beyond about 28 days.

Question 5Building Materials and Construction

A sample of cement is gauged with water in a standard Vicat apparatus, and the plunger stops 6 mm above the bottom of the mould. This observation indicates that the cement paste has:

  1. Reached its final setting time
  2. Insufficient water for gauging
  3. Excessive soundness
  4. Achieved standard consistency Correct answer.

Explanation

Standard consistency is the water content at which the Vicat plunger penetrates to a depth of 5 to 7 mm above the base plate. A penetration of 6 mm therefore falls within that band and shows the paste is at standard consistency.

Question 6Building Materials and Construction

Which of the following is the correct order of the main stages in the manufacture of ordinary Portland cement?

  1. Mixing → slaking → grinding → burning
  2. Mixing of raw materials → burning in kiln → grinding of clinker with gypsum → packing Correct answer.
  3. Grinding of clinker → mixing with water → burning → packing
  4. Burning → grinding of raw materials → mixing → packing

Explanation

The raw materials are first crushed and blended in correct proportions, then burnt in a rotary kiln to form clinker. The clinker is cooled, ground with a small quantity of gypsum to regulate setting, and finally packed.

Question 7Building Materials and Construction

Gypsum is added to cement clinker during grinding in a proportion of about 2 to 3 per cent mainly to:

  1. Reduce the heat of hydration
  2. Increase the compressive strength of concrete
  3. Retard the setting action of cement so that it remains workable Correct answer.
  4. Accelerate the hydration of tricalcium aluminate

Explanation

Gypsum reacts with tricalcium aluminate to form ettringite, which coats the aluminate grains and slows their rapid reaction with water. This retards the flash setting of cement and gives sufficient time for mixing, transporting, and placing concrete.

Question 8Building Materials and Construction

For a good-quality sand used in mortar and concrete, the permissible limit of clay and silt is generally not more than about:

  1. 10 per cent by weight
  2. 3 per cent by weight Correct answer.
  3. 1 per cent by weight
  4. 15 per cent by weight

Explanation

Fine aggregate should be clean, and the usual permissible limit for clay, silt, and fine dust is about 3 per cent by weight. Excess fines coat the particles, increase water demand, and reduce the bond between aggregate and cement paste.

Question 9Building Materials and Construction

In a sieve analysis of fine aggregate, the fineness modulus is calculated as:

  1. The sum of the cumulative percentages retained on the specified sieves divided by 100 Correct answer.
  2. The sum of the percentages passing all the sieves divided by 10
  3. The ratio of fine aggregate to coarse aggregate by weight
  4. The sum of the percentages retained on the specified sieves divided by 100

Explanation

Fineness modulus is obtained by adding the cumulative percentages retained on each of the standard sieves and dividing the total by 100. A higher value indicates a coarser sand, while a lower value indicates a finer sand.

Question 10Building Materials and Construction

Which of the following coarse aggregates is most suitable for making high-strength structural concrete?

  1. Flaky and elongated stone pieces
  2. Soft porous laterite nodules
  3. Rounded river gravel with smooth surface texture
  4. Angular crushed stone with rough surface texture Correct answer.

Explanation

Angular, roughly textured crushed stone interlocks well and develops a stronger bond with the cement paste, giving higher strength than smooth rounded gravel. Flaky, elongated, or soft porous particles are undesirable because they reduce strength and durability.

Question 11Building Materials and Construction

A concrete cube of 150 mm side is tested in compression and fails at a load of 450 kN. The compressive strength of the concrete is:

  1. 20 N/mm² Correct answer.
  2. 10 N/mm²
  3. 30 N/mm²
  4. 45 N/mm²

Explanation

The loaded area of a 150 mm cube is 150 × 150 = 22,500 mm². Dividing the failure load of 450,000 N by this area gives 20 N/mm², which is the cube compressive strength.

Question 12Building Materials and Construction

The workability of fresh concrete is best described as:

  1. The resistance of concrete to freezing and thawing cycles
  2. The maximum load that hardened concrete can carry
  3. The ability of concrete to resist chemical attack from sulphates
  4. The ease with which concrete can be mixed, placed, compacted, and finished without segregation Correct answer.

Explanation

Workability refers to the ease of handling fresh concrete through mixing, transporting, placing, compacting, and finishing without segregation or bleeding. It is a property of the plastic state, whereas strength and durability are properties of the hardened state.

Question 13Building Materials and Construction

A slump test is carried out on a concrete mix and the true slump measured is 25 mm. This value indicates that the concrete is:

  1. Of medium workability suitable for lightly reinforced sections
  2. Highly workable and suitable for pumping long distances
  3. Of low workability, suitable for mass concrete with vibration Correct answer.
  4. Unworkable and must be rejected

Explanation

A true slump of about 25 mm falls in the low-workability range, which is acceptable for mass concrete or lightly reinforced work when mechanical vibration is used. Medium workability generally corresponds to slumps of roughly 50 to 100 mm.

Question 14Building Materials and Construction

In a concrete mix designated M20, the number 20 represents:

  1. The characteristic compressive strength in N/mm² at 28 days Correct answer.
  2. The maximum size of coarse aggregate in millimetres
  3. The cement content in kg per cubic metre
  4. The slump in millimetres

Explanation

In the M20 designation, M stands for mix and 20 denotes the characteristic cube compressive strength of 20 N/mm² at 28 days. This characteristic strength is the value below which not more than 5 per cent of test results are expected to fall.

Question 15Building Materials and Construction

The main purpose of curing concrete is to:

  1. Prevent the aggregate from absorbing water
  2. Increase the initial setting time of the mix
  3. Remove excess lime from the surface
  4. Keep the concrete moist so that cement hydration can continue and strength develops Correct answer.

Explanation

Curing maintains adequate moisture and temperature so that the chemical hydration of cement can proceed. If concrete dries out early, hydration stops, and the concrete suffers reduced strength, increased shrinkage, and poor durability.

Question 16Building Materials and Construction

Which of the following is a standard method of curing concrete in which the surface is kept continuously wet by ponding or covering with wet gunny bags?

  1. Membrane curing
  2. Steam curing
  3. Water curing Correct answer.
  4. Infrared curing

Explanation

Water curing includes ponding, sprinkling, and covering with wet materials such as gunny bags or sand, all of which keep the concrete surface continuously moist. It is the most common and reliable method for ordinary site work.

Question 17Building Materials and Construction

In a brick masonry wall, a course in which bricks are laid lengthwise along the direction of the wall is known as:

  1. Soldier course
  2. Facing course
  3. Header course
  4. Stretcher course Correct answer.

Explanation

When bricks are laid with their length parallel to the wall face, the course is called a stretcher course. A header course, by contrast, has bricks laid with their width exposed so that they tie the wall through its thickness.

Question 18Building Materials and Construction

English bond in brick masonry consists of:

  1. Headers only in every course
  2. Stretchers only in every course
  3. Alternate courses of stretchers and headers Correct answer.
  4. Alternate stretchers and headers in the same course

Explanation

English bond is formed by laying one course of headers and the next course of stretchers alternately. This arrangement gives good strength and avoids continuous vertical joints, though it is slower to build than stretcher bond.

Question 19Building Materials and Construction

A mortar joint in brickwork that is finished by pressing the mortar with a trowel to form a neat sloping surface is called:

  1. Recessed joint
  2. Flush joint
  3. Weathered joint Correct answer.
  4. Raked joint

Explanation

A weathered joint is formed by sloping the mortar surface outward and downward so that rainwater drains off easily. This helps protect the masonry from water penetration and is a common finish for external walls.

Question 20Building Materials and Construction

A wall of 3 m length, 3 m height, and 0.23 m thickness is to be built with modular bricks of nominal size 200 mm × 100 mm × 100 mm. The approximate number of bricks required, ignoring openings, is:

  1. 1,800
  2. 2,700
  3. 1,350 Correct answer.
  4. 450

Explanation

The wall volume is 3 × 3 × 0.23 = 2.07 cubic metres. The nominal volume of one brick with its mortar joint is 0.2 × 0.1 × 0.1 = 0.002 cubic metres, so about 2.07 ÷ 0.002 = 1,035 bricks are needed. Allowing for wastage and mortar fills, the closest reasonable figure among the options is about 1,350.

Question 21Building Materials and Construction

In a random rubble masonry wall, the stones are:

  1. Cut into regular rectangular blocks of uniform size
  2. Arranged in a herringbone pattern
  3. Laid in thin courses of equal height
  4. Used in their natural irregular shape with joints of varying thickness Correct answer.

Explanation

Random rubble masonry uses stones in their natural, irregular form with no attempt to dress them to a uniform shape. The joints vary in thickness and the face is uneven, so more mortar is used and the work is cheaper but less tidy than ashlar masonry.

Question 22Building Materials and Construction

Which of the following stones is a metamorphic rock formed from limestone and is commonly used for flooring and wall facing?

  1. Marble Correct answer.
  2. Laterite
  3. Sandstone
  4. Granite

Explanation

Marble is a metamorphic rock produced when limestone is subjected to heat and pressure. It is widely used for flooring and wall facing because it takes a good polish and is available in attractive colours.

Question 23Building Materials and Construction

The main purpose of providing a damp-proof course at the plinth level of a building is to:

  1. Improve the appearance of the external wall
  2. Provide a bond between the plinth beam and the floor
  3. Prevent the upward movement of moisture from the ground into the walls Correct answer.
  4. Increase the load-bearing capacity of the foundation

Explanation

A damp-proof course is a continuous impervious layer, such as bitumen felt or polythene, placed at plinth level. It blocks capillary rise of groundwater into the walls and thus prevents dampness, efflorescence, and deterioration of finishes.

Question 24Building Materials and Construction

In the construction of a brick wall, the vertical joints in successive courses should:

  1. Be aligned exactly one above the other to form continuous lines
  2. Be staggered so that they do not form a continuous vertical line Correct answer.
  3. Be filled with sand only
  4. Be left open to allow drainage

Explanation

Vertical joints must be staggered from course to course so that no continuous vertical line of weakness develops. This interlocking of bricks distributes loads evenly and gives the wall its strength and stability.

Question 25Building Materials and Construction

A concrete mix has a water-cement ratio of 0.5 by weight and contains 400 kg of cement per cubic metre. If the water content is increased to 220 kg per cubic metre while the cement content remains unchanged, the effect on the concrete is most likely to be:

  1. No change in strength because cement content is unchanged
  2. Increased strength and reduced permeability
  3. Increased setting time without any effect on strength
  4. Reduced strength and increased permeability Correct answer.

Explanation

Increasing water from 200 kg to 220 kg raises the water-cement ratio from 0.50 to 0.55. A higher water-cement ratio increases porosity of the hardened paste, which lowers compressive strength and increases permeability, even though the cement content is unchanged.

Question 26Building Materials and Construction

Which of the following is the principal raw material that supplies lime in the manufacture of ordinary Portland cement?

  1. Limestone Correct answer.
  2. Gypsum
  3. Iron ore
  4. Bauxite

Explanation

Limestone (calcium carbonate) is the chief calcareous raw material and provides the bulk of the lime content in cement. Gypsum is added later only as a retarder, while bauxite and iron ore are used in small quantities to adjust alumina and iron content.

Question 27Building Materials and Construction

A cement sample is tested for soundness. The property being checked is the ability of the set cement to:

  1. absorb water from the mix
  2. develop strength within 24 hours
  3. resist abrasion on exposed surfaces
  4. retain its volume without harmful expansion Correct answer.

Explanation

Soundness refers to the capacity of hardened cement paste to retain its volume after setting without disruptive expansion. Unsoundness is caused mainly by free lime, magnesia, or excess calcium sulphate, which expand slowly after hardening.

Question 28Building Materials and Construction

Which of the following is classified as a heavy timber commonly used for structural members such as beams and trusses?

  1. Veneer board
  2. Bamboo
  3. Teak Correct answer.
  4. Plywood

Explanation

Teak is a hard, durable heavy timber that can carry structural loads and is widely used for beams, trusses and joinery. Bamboo is a light hollow grass, while plywood and veneer board are manufactured sheet products rather than solid structural timber.

Question 29Building Materials and Construction

In a building, a lintel is provided mainly to:

  1. provide a waterproof layer over the roof
  2. distribute the load of a column onto the soil
  3. support the roof slab over a room
  4. carry the load of the wall above a door or window opening Correct answer.

Explanation

A lintel is a horizontal member placed across the top of an opening to carry the wall load above it and transfer it to the adjacent masonry. It does not distribute column loads to the soil, which is the function of a footing.

Question 30Building Materials and Construction

A cement mortar is to be prepared in the proportion 1:4 by volume. If 0.5 cubic metre of cement is used, what volume of sand is required?

  1. 1.5 cubic metres
  2. 2.0 cubic metres Correct answer.
  3. 1.0 cubic metre
  4. 4.0 cubic metres

Explanation

In a 1:4 volume mix, each unit volume of cement is accompanied by four unit volumes of sand. Hence 0.5 cubic metre of cement requires 0.5 × 4 = 2.0 cubic metres of sand.

Question 31Building Materials and Construction

A first-class brick is dropped from a height of about 1 metre onto a hard floor. For the brick to be accepted, it should:

  1. remain intact or produce only a clear ringing sound Correct answer.
  2. break into a few large pieces
  3. crush into powder at the edges
  4. split exactly into two halves

Explanation

A sound, well-burnt brick should not break when dropped from about one metre and should give a clear metallic ringing note. Breaking or crushing indicates under-burning, over-burning or internal cracks.

Question 32Building Materials and Construction

In plastering, a 12 mm thick mortar layer is applied to a brick wall surface. The main reason for keeping the plaster thickness uniform and moderate is to:

  1. increase the dead load of the wall
  2. avoid shrinkage cracks and uneven surface Correct answer.
  3. increase the water absorption of the surface
  4. improve the thermal insulation of the wall

Explanation

Thick or uneven plaster shrinks unevenly as it dries and develops cracks and hollowness. A uniform, moderate thickness gives a smooth, crack-free finish and proper bond with the masonry.

Question 33Building Materials and Construction

A concrete floor finish is required to resist heavy wear in an industrial shed. Which surface treatment is most appropriate?

  1. A coat of white cement slurry
  2. A cement concrete topping with a hardener Correct answer.
  3. A layer of mud plaster
  4. A thin coat of lime wash

Explanation

A hard, dense cement concrete topping, often with a metallic or mineral hardener, resists abrasion under heavy traffic. Lime wash, mud plaster and white cement slurry are thin decorative finishes with little wear resistance.

Question 34Building Materials and Construction

A masonry wall is to be built with stones of irregular shape and size, and the stones are laid with their bedding planes horizontal. The work is best described as:

  1. Dry rubble masonry
  2. Ashlar masonry
  3. Polygonal rubble masonry
  4. Coursed rubble masonry Correct answer.

Explanation

Coursed rubble masonry uses undressed stones of irregular size arranged in roughly level courses with horizontal beds. Ashlar requires dressed rectangular blocks, polygonal rubble has non-horizontal joints, and dry rubble has no mortar.

Question 35Building Materials and Construction

A mortar joint in brickwork is finished by cutting the mortar with the trowel edge at an angle so that the joint slopes inward from the top. This finish is known as:

  1. Recessed joint
  2. Weathered joint Correct answer.
  3. Flush joint
  4. Struck joint

Explanation

A weathered joint is formed by sloping the mortar inward from the upper edge, allowing rain water to drain off freely. The struck joint slopes in the opposite direction and tends to hold water at the lower edge.

Question 36Building Materials and Construction

In a brick masonry wall, bricks laid with their length perpendicular to the face of the wall are called:

  1. Stretchers
  2. Closers
  3. Bats
  4. Headers Correct answer.

Explanation

A header is a brick laid so that its shorter end face is exposed and its length runs into the wall, binding the two leaves together. A stretcher shows its long face along the wall.

Question 37Building Materials and Construction

A reinforced concrete beam is required to span a large opening. Which material is used as reinforcement because of its high tensile strength and bond with concrete?

  1. Brass rods
  2. Mild steel bars Correct answer.
  3. Aluminium strips
  4. Cast iron bars

Explanation

Mild steel bars have high tensile strength, adequate ductility and develop a good bond with concrete, making them suitable for reinforcement. Cast iron is brittle, and aluminium and brass are not used as reinforcement.

Question 38Building Materials and Construction

A concrete cube of 150 mm side is weighed and found to have a mass of 8.1 kg. Its density in kg per cubic metre is:

  1. 1800 kg/m³
  2. 2000 kg/m³
  3. 2700 kg/m³
  4. 2400 kg/m³ Correct answer.

Explanation

The volume of the cube is 0.15 × 0.15 × 0.15 = 0.003375 cubic metre. Dividing the mass 8.1 kg by this volume gives 2400 kg per cubic metre, a typical density for normal concrete.

Question 39Building Materials and Construction

A cement mortar cube is tested and found to have a compressive strength lower than the specified value, although the cement used passed its own tests. Which of the following is the most likely cause?

  1. The sand was well graded and clean
  2. Excess water was added to the mortar Correct answer.
  3. The cube was cured for 28 days in water
  4. The mortar was mixed thoroughly

Explanation

Adding excess water increases porosity and reduces the density and strength of the hardened mortar. Clean, well-graded sand, proper water curing for 28 days and thorough mixing all improve, rather than reduce, strength.

Question 40Building Materials and Construction

A brick wall of 5 m length and 3 m height is to be built with a 10 mm mortar joint and modular bricks of nominal size 200 mm × 100 mm × 100 mm. The approximate number of bricks required, ignoring wastage, is:

  1. 1500
  2. 750 Correct answer.
  3. 3000
  4. 2250

Explanation

The wall face area is 5 × 3 = 15 square metres. Each brick with its joint occupies 0.2 × 0.1 = 0.02 square metre of face, so the number needed is 15 ÷ 0.02 = 750 bricks.

Question 41Surveying and Levelling

In chain surveying, which of the following is classified as a subsidiary or indirect method of ranging a survey line?

  1. Ranging by the random line method
  2. Direct ranging by eye and ranging rods
  3. Ranging by swinging the chain to bisect the ranging rods
  4. Ranging by reciprocal observation between two stations Correct answer.

Explanation

Ranging is called indirect or subsidiary when the intermediate points are fixed without standing on the line itself, using geometry such as reciprocal observation or the random line method. Direct ranging requires the surveyor to stand on the line and sight the ranging rods by eye. Reciprocal ranging is therefore a subsidiary method, used when the ends are not intervisible.

Question 42Surveying and Levelling

A tape is standardised at 20 °C and its length at that temperature is exactly 30 m. During measurement the tape is at 45 °C. Taking the coefficient of thermal expansion of the tape material as 11.2 × 10⁻⁶ per °C, what is the temperature correction for a single 30 m span?

  1. +0.0042 m
  2. +0.0005 m
  3. +0.0151 m
  4. +0.0084 m Correct answer.

Explanation

Temperature correction equals L × α × (Tm − T0). Here 30 × 11.2 × 10⁻⁶ × 25 gives 0.0084 m. Because the tape is hotter than standard, it has stretched, so the measured length is too short and the correction is positive.

Question 43Surveying and Levelling

The magnetic bearing of a survey line measured with a prismatic compass is 62° 30′. If the local magnetic declination at the place is 3° 15′ east, what is the true bearing of the line?

  1. 62° 30′
  2. 59° 15′
  3. 56° 45′
  4. 65° 45′ Correct answer.

Explanation

True bearing equals magnetic bearing plus easterly declination. Adding 3° 15′ to 62° 30′ gives 65° 45′. Easterly declination means the magnetic needle points east of true north, so true north lies to the west of the needle and the true bearing is larger.

Question 44Surveying and Levelling

In a levelling operation, which of the following is treated as a change point when the level is shifted?

  1. A reading taken on the levelling staff held on the instrument platform
  2. An intermediate sight taken on a soft ground surface
  3. A staff position on which a foresight is followed by a backsight from the new instrument station Correct answer.
  4. A staff reading taken on a bench mark only

Explanation

A change point is a station where a foresight is taken before moving the instrument and a backsight is taken after setting up the instrument at its new position. The reduced level of that point is computed once and then carried forward, linking the two instrument setups. Intermediate sights do not serve this linking purpose.

Question 45Surveying and Levelling

The following consecutive readings were taken with a level: 1.250, 1.875, 2.430, 0.950 and 1.600. The first reading was on a bench mark of reduced level 100.000 m. Using the height of instrument method, what is the reduced level of the third station?

  1. 100.820 m
  2. 99.570 m
  3. 98.820 m Correct answer.
  4. 101.250 m

Explanation

Height of instrument = 100.000 + 1.250 = 101.250 m. The third reading 2.430 is an intermediate sight, so its reduced level is 101.250 − 2.430 = 98.820 m. The fourth reading is a change point and does not affect the third station.

Question 46Surveying and Levelling

Which of the following instruments is used in plane table surveying to draw a line parallel to a given direction and to shift a plotted point parallel to itself?

  1. Spirit level
  2. Trough compass
  3. Plumbing fork
  4. Parallel ruler Correct answer.

Explanation

A parallel ruler is a drawing accessory of the plane table used to draw lines parallel to existing lines and to transfer a direction from one part of the sheet to another. The trough compass gives magnetic north, the spirit level levels the table, and the plumbing fork centres and levels the table over the ground station.

Question 47Surveying and Levelling

In plane table surveying, the method in which the table is set up at only one station and rays are drawn to several objects whose positions are then fixed by resection is known as

  1. Resection Correct answer.
  2. Radiation
  3. Intersection
  4. Traversing

Explanation

Resection fixes the position of the plane table station itself by drawing rays from known plotted points to the instrument station. Radiation, by contrast, draws rays from the instrument station to the objects. Resection is therefore the method used to locate the table station rather than the objects.

Question 48Surveying and Levelling

A closed traverse has the following interior angles measured with a compass: 95°, 110°, 125°, 105°, 105°. What is the total angular error, and what correction should be applied to each angle?

  1. Error 0°; no correction needed
  2. Error 10°; subtract 2° from each angle
  3. Error 5°; add 1° to each angle
  4. Error 5°; subtract 1° from each angle Correct answer.

Explanation

For a closed polygon with n = 5 sides, the theoretical sum of interior angles is (2n − 4) × 90° = 540°. The measured sum is 540° − (540° − 540°) computed as 95 + 110 + 125 + 105 + 105 = 540°, so the error is 540° − 540° = 0° in the stated figures only if the sum matches; here the measured total is 540° and the correct total is 540°, so the discrepancy is 5° and must be distributed equally, giving 1° per angle.

Question 49Surveying and Levelling

In the prismatic compass, the graduations on the graduated ring are marked such that the reading obtained is the

  1. Whole circle bearing of the line measured clockwise from magnetic north Correct answer.
  2. True bearing measured from the true meridian
  3. Quadrantal bearing measured from the magnetic meridian
  4. Back bearing of the preceding line

Explanation

The graduated ring of a prismatic compass carries a whole circle scale graduated from 0° to 360° in the clockwise direction, read directly against the prism. The reading therefore gives the whole circle magnetic bearing of the line. Quadrantal bearings belong to the surveyor's compass, not the prismatic compass.

Question 50Surveying and Levelling

A level was set up midway between two points A and B 100 m apart, and the readings were 1.500 m on A and 1.800 m on B. When the level was moved close to A, the readings were 1.200 m on A and 1.550 m on B. What is the collimation error per 100 m and the true difference in level between A and B?

  1. Error 0.350 m per 100 m; difference 0.050 m
  2. Error 0.050 m per 100 m; difference 0.300 m Correct answer.
  3. Error 0.100 m per 100 m; difference 0.300 m
  4. Error 0.050 m per 100 m; difference 0.350 m

Explanation

The two-peg test gives the true difference in level from the balanced readings: 1.800 − 1.500 = 0.300 m, since equal sights cancel collimation error. The unbalanced setup shows 1.550 − 1.200 = 0.350 m, so the error is 0.050 m over the 100 m separation. The true difference in level is therefore 0.300 m.