23 extra multiple-choice questions for Surveying (12th Standard Geography, Samacheer Kalvi), beyond the ones printed in the textbook — each with the correct option highlighted and a clear, worked explanation. Free to read in English and Tamil.
Q1
The science of measuring and recording distances, angles, heights and sizes of the earth's surface to obtain data from which accurate plans and maps are made is called
- A. SurveyingCorrect
- B. Levelling
- C. Bearing
- D. Traverse
Explanation. The lesson defines surveying as the science of measuring and recording distances, angles, heights and sizes of the earth's surface to obtain data from which accurate plans and maps are made.
Q2
According to the lesson, which is the most essential piece of equipment used by the geographer, engineer and architect?
- A. Clinometer
- B. Prismatic compass
- C. MapCorrect
- D. Measuring tape
Explanation. The lesson states that the map is the most essential piece of equipment which the geographer, engineer and architect use, so geographers must learn to read, make and use maps.
Q3
Consider the following statements:
1) A clinometer is used to measure the height of a tall object.
2) A prismatic compass measures the vertical angle of an object above eye-level.
Which of the statements given above is/are correct?
- A. 1 onlyCorrect
- B. 2 only
- C. Both 1 and 2
- D. Neither 1 nor 2
Explanation. Clinometers are used to measure the height of a tall object. The prismatic compass measures the horizontal angle with reference to the magnetic north line, not a vertical angle, so statement 2 is wrong.
Q4
Find the odd one out from the things needed to measure the height of a tall object with a clinometer, as listed in the lesson.
- A. Tape
- B. Assistant
- C. Prismatic compassCorrect
- D. Paper and pencil
Explanation. For the clinometer exercise the lesson lists clinometers, tape, paper, pen or pencil and an assistant. The prismatic compass is not needed; it is used to measure horizontal angles.
Q5
While picking a spot to measure the height of a tree with a clinometer, the observer should
- A. stand far enough away to see the top of the tree, on level ground with its baseCorrect
- B. stand at the base of the tree and look straight up
- C. stand on raised ground well above the base of the tree
- D. stand so close that the top of the tree cannot be seen
Explanation. In Step 1 the observer must be far enough away from the object to see its top, and must be on level ground with the base of the object.
Q6
Looking through the straw at the top of a tree, the clinometer reads 55°. What is the angle of vision from the eye to the top of the tree?
- A. 55°
- B. 35°Correct
- C. 90°
- D. 145°
Explanation. The angle shown on the clinometer is subtracted from 90°. In the lesson's example the clinometer showed 55°, and 90° - 55° = 35°, the angle at which we looked to the top of the tree.
Q7
Which instrument is used to find the distance from the observer's spot to the base of the object being measured?
- A. Clinometer
- B. TapeCorrect
- C. Prismatic compass
- D. Protractor
Explanation. In Step 3 a tape measure is used to find the distance from the spot where we stand to the base of the object. In the example this distance was 15.6 metres.
Q8
Arrange the first four steps of measuring height with a clinometer in the correct order.
1) Measure distance
2) Pick a spot
3) Find your eye-height
4) Measure angle
- A. 2, 4, 1, 3Correct
- B. 2, 1, 4, 3
- C. 4, 2, 3, 1
- D. 2, 4, 3, 1
Explanation. The lesson orders the steps as: pick a spot, measure angle, measure distance, find your eye-height. Drawing a picture, modelling a triangle and combining with eye-height follow.
Q9
Which trigonometric ratio of the right triangle is used to find the height of the object above eye-level?
- A. Sine
- B. Cosine
- C. TangentCorrect
- D. Secant
Explanation. The lesson uses the tangent ratio: tan(angle) = x / distance, so x = tan(angle) × distance, where x is the portion of the height from eye-level up.
Q10
In the lesson's example, the angle of vision is 35° and the distance from the tree is 15.6 m. Taking tan 35° = 0.7002, the height of the tree above eye-level (x) is
- A. 12.56 m
- B. 10.92 mCorrect
- C. 15.60 m
- D. 9.28 m
Explanation. x = tan 35° × distance = 0.7002 × 15.6 = 10.92 m (10.923 rounded). This is the height from eye-level up, before the eye-height is added.
Q11
In the lesson's example, x = 10.92 m and the observer's eye-height is 1.64 m. What is the height (h) of the tree?
- A. 9.28 m
- B. 10.92 m
- C. 12.56 mCorrect
- D. 17.24 m
Explanation. Step 7 combines x with the eye-height: h = x + (eye-height) = 10.92 m + 1.64 m = 12.56 m.
Q12
Using the lesson's method, an observer with an eye-height of 1.5 m stands 20 m from a pole and finds the angle of vision to its top is 35°. Taking tan 35° = 0.7002, the height of the pole is
- A. 14.004 m
- B. 15.504 mCorrect
- C. 21.500 m
- D. 12.504 m
Explanation. x = tan 35° × distance = 0.7002 × 20 = 14.004 m. Then h = x + eye-height = 14.004 + 1.5 = 15.504 m.
Q13
Assertion (A): After finding x from the right triangle, the eye-height must be added to get the height of the object.
Reason (R): x represents only the portion of the height of the object from eye-level up.
- A. Both A and R are true and R is the correct explanation of ACorrect
- B. Both A and R are true but R is not the correct explanation of A
- C. A is true but R is false
- D. A is false but R is true
Explanation. The triangle gives x, the height from eye-level up. So Step 7 adds the eye-height measured earlier: h = x + (eye-height). R explains why A is needed.
Q14
When the observer's system is first modelled as a right triangle (Step 6), which measurement is not needed yet?
- A. The angle read on the clinometer
- B. The distance from the object
- C. The eye-height of the observerCorrect
- D. The position of the observer
Explanation. In Step 6 the triangle is labelled with the angle read on the clinometer and the distance from the object. The lesson notes that the eye-height is not needed yet; it is added in Step 7.
Q15
The aluminium ring of a prismatic compass is graduated to
- A. 1 degree
- B. 10 minutes
- C. 15 minutes
- D. 30 minutesCorrect
Explanation. The prismatic compass is a simple instrument comprising an aluminium ring graduated to 30 minutes, held at the top of a broad magnetic needle.
Q16
In a prismatic compass, the two coloured sunglasses set at a hinge are meant to
- A. magnify the degree marking on the ring
- B. avoid direct sun rays at the eye vaneCorrect
- C. stop the oscillating ring
- D. locate very high objects by reflection
Explanation. Two coloured sunglasses are set at a hinge on the eye-vane side of the prismatic compass to avoid direct sun rays at the eye vane.
Q17
The sighting vane of a prismatic compass has a horse hair at the centre of a hinged metal frame. In reality this horse hair may be
- A. a fine silk thread or a metal wireCorrect
- B. a magnetic needle
- C. a glass prism
- D. a coloured glass
Explanation. The sighting vane consists of a hinged metal frame with a horse hair at the centre. The lesson states that this horse hair in reality may be a fine silk thread or a metal wire.
Q18
Why is a hinged adjustable mirror set on the outer side of the sighting vane of a prismatic compass?
- A. To avoid direct sun rays at the eye vane
- B. To bring the oscillating ring to a standstill
- C. To locate a too high or too low object through reflectionCorrect
- D. To level the compass on its stand
Explanation. A hinged adjustable mirror is set on the outer side of the sighting vane in order to locate a too high or too low object through reflection.
Q19
Which part of a prismatic compass brings the oscillating circular ring to a standstill?
- A. Sighting vane
- B. Brake pin or knobCorrect
- C. Prism
- D. Sunglasses
Explanation. The lesson states that there is a brake pin or knob which brings the oscillating circular ring of the prismatic compass to a standstill.
Q20
Match the parts of a prismatic compass with their functions.
A) Prism - 1) Brings the oscillating ring to a standstill
B) Sunglasses - 2) Avoid direct sun rays at the eye vane
C) Adjustable mirror - 3) Magnifies the degree marking on the aluminium ring
D) Brake pin - 4) Locates a too high or too low object
- A. A-3, B-2, C-4, D-1Correct
- B. A-2, B-3, C-1, D-4
- C. A-3, B-4, C-2, D-1
- D. A-4, B-2, C-3, D-1
Explanation. The prism magnifies the degree marking on the ring, the sunglasses avoid direct sun rays, the adjustable mirror locates too high or too low objects by reflection, and the brake pin stops the oscillating ring.
Q21
Consider the following statements about the use of a prismatic compass:
1) The corners of a plot or building can be measured directly.
2) The bends of a road can be measured directly.
3) A meandering canal can be measured only as a whole, without dividing it into segments.
Which of the statements given above is/are correct?
- A. 1 only
- B. 1 and 2 onlyCorrect
- C. 2 and 3 only
- D. 1, 2 and 3
Explanation. The corners of a plot or building and the bends of a road can be measured directly. The bends of a meandering canal are favourably determined after dividing it into segments, so statement 3 is wrong.
Q22
A prismatic compass measures the horizontal angle with reference to the
- A. magnetic north lineCorrect
- B. eye-level line
- C. base of the object
- D. top of the object
Explanation. The lesson states that the prismatic compass measures the horizontal angle with reference to the magnetic north line.
Q23
In a prismatic compass, the ball and socket arrangement at the base is used for
- A. magnifying the ring markings
- B. levellingCorrect
- C. stopping the needle
- D. reflecting high objects
Explanation. The lesson names it the ball and socket arrangement for levelling. The metal box has a threaded bottom screwed to a ball fitted and adjustable in a socket of the compass stand.
