Surveying and Levelling

251. The construction of optical square is based, on the principle of optical

1. Reflection
2. Refraction
3. Double refraction
4. Double reflection

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252. The co-ordinate of a point measured perpendicular to the parallel, is called

1. Total latitude
2. Meridian distance
3. Total departure
4. Consecutive co-ordinate

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253. The correction to be applied to each 30 metre chain length along θ° slop, is

1. 30 (secθ - 1) m
2. 30 (sinθ - 1) m
3. 30 (cosθ - 1) m
4. 30 (taanθ - 1) m

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254. The curvature of the earth's surface, is taken into account only if the extent of survey is more than

1. 100 sq km
2. 160 sq km
3. 200 sq km
4. 260 sq km

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255. The curve composed of two arcs of different radii having their centres on the opposite side of the curve, is known

1. A simple curve
2. A compound curve
3. A reverse curve
4. A vertical curve

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256. The defect of a lens whereby rays of white light proceeding from a point get dispersed into their components and conveyed to various foci, forming a blurred and coloured image is known as

1. Chromatic aberration
2. Spherical aberration
3. Astigmatism
4. Coma

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257. The desired sensitivity of a bubble tube with 2 mm divisions is 30". The radius of the bubble tube should be

1. 13.75 m
2. 3.44 m
3. 1375 m
4. None of these

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258. The diaphragm of a stadia theodolite is fitted with two additional

1. Horizontal hairs
2. Vertical hairs
3. Horizontal and two vertical hairs
4. None of these

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259. The difference in the lengths of an arc and its subtended chord on the earth surface for a distance of 18.2 km, is only

1. 1 cm
2. 5 cm
3. 10 cm
4. 100 cm

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260. The difference of level between a point below the plane of sight and one above, is the sum of two staff readings and an error would be produced equal to

1. The distance between the zero of gradient and the foot of the staff
2. Twice the distance between the zero of graduation and the foot of the staff
3. Thrice the distance between the zero of graduation and the foot of the staff
4. None of the above

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