Compass Surveying Questions and Answers

Q: The difference between Fore Bearing and Back Bearing of a traverse line is

The difference is exactly 180°.The fore bearing of a line AB is its direction measured at A, looking towards B. The back bearing is the direction of the same line measured at B, looking back towards A. Since these are two opposite directions along one straight line, their whole circle bearings differ by exactly 180°: BB = FB ± 180°.If the observed difference is not 180°, that signals local attraction at one of the stations or an observation error, and the bearings must be corrected. A difference of 90°, or anything less or more than 180°, never holds for a correctly observed line.

Q: If WCB (Whole circle bearing ) of AB is 125° 45′, then find the value of quadrant bearing (AB).

The quadrant bearing is S 54° 15′ E.A whole circle bearing between 90° and 180° lies in the south-east quadrant, and its reduced bearing is measured from south.\[ \text{RB} = 180^\circ - 125^\circ 45' = 54^\circ 15' \]So AB is S 54° 15′ E. S 125° 45′ E is impossible, since a reduced bearing never exceeds 90°, and 52° 15′ and 53° 15′ are subtraction slips.

Q: The Magnetic bearing of line AB is 135° 30′. What will be the true bearing, if the declination is 5° 15′ W?

The true bearing is 130° 15′.With a westerly declination, magnetic north lies west of true north, so magnetic bearings are larger than true ones. True bearing = magnetic bearing minus the west declination.\[ 135^\circ 30' - 5^\circ 15' = 130^\circ 15' \]140° 45′ adds the declination, which would be correct for an easterly declination. 130° 45′ is a slip in the minutes, and 135° 30′ ignores declination.

Q: The vertical angle between longitudinal axis of a freely suspended magnetic needle and a horizontal line at its pivot, is known as:

The angle is called the dip.A freely suspended magnetic needle aligns with the Earth's magnetic field, which is inclined to the horizontal everywhere except at the magnetic equator. The vertical angle between the needle and the horizontal is the dip or inclination; it is zero at the magnetic equator and 90° at the magnetic poles. Compass needles carry a small rider to counteract it.Declination is the horizontal angle between the magnetic and true meridians. Azimuth and bearing are horizontal directions of a line, not vertical angles.

Q: If Fore bearing of a line is S 49°52'E (assuming there is no local attraction), the back bearing of the line will be :

The back bearing is N 49°52'W.In the quadrantal (reduced bearing) system, the back bearing has the same angle as the fore bearing with both letters reversed: N becomes S and E becomes W, and the other way round. So S 49°52'E becomes N 49°52'W, with no local attraction to correct for.S 49°52'E is the fore bearing repeated, S 52°49'E swaps the degrees and minutes, and N 49°08'E changes the angle and reverses only one letter.

The difference between Fore Bearing and Back Bearing of a traverse line is

A.exactly 90°
B.less than 180°
C.exactly 180°
D.greater than 180°

Exam Year(s)

GATE AG - 2012,

Answer: C

The difference is exactly 180°.

The fore bearing of a line AB is its direction measured at A, looking towards B. The back bearing is the direction of the same line measured at B, looking back towards A. Since these are two opposite directions along one straight line, their whole circle bearings differ by exactly 180°: BB = FB ± 180°.

If the observed difference is not 180°, that signals local attraction at one of the stations or an observation error, and the bearings must be corrected. A difference of 90°, or anything less or more than 180°, never holds for a correctly observed line.

Discuss in Forum

If WCB (Whole circle bearing ) of AB is 125° 45′, then find the value of quadrant bearing (AB).

A.S 52° 15′E
B.S 125°45′E
C.S 54° 15′E
D.S 53° 15′E

Exam Year(s)

RSMSSB JE - 2025, RSMSSB JE Agriculture - 2025, RSMSSB - 2025,

Answer: C

The quadrant bearing is S 54° 15′ E.

A whole circle bearing between 90° and 180° lies in the south-east quadrant, and its reduced bearing is measured from south.

\[ \text{RB} = 180^\circ - 125^\circ 45' = 54^\circ 15' \]

So AB is S 54° 15′ E. S 125° 45′ E is impossible, since a reduced bearing never exceeds 90°, and 52° 15′ and 53° 15′ are subtraction slips.

Discuss in Forum

The Magnetic bearing of line AB is 135° 30′. What will be the true bearing, if the declination is 5° 15′ W?

A.140° 45′
B.135°30′
C.130° 45′
D.130° 15′

Exam Year(s)

RSMSSB JE - 2025, RSMSSB JE Agriculture - 2025, RSMSSB - 2025,

Answer: D

The true bearing is 130° 15′.

With a westerly declination, magnetic north lies west of true north, so magnetic bearings are larger than true ones. True bearing = magnetic bearing minus the west declination.

\[ 135^\circ 30' - 5^\circ 15' = 130^\circ 15' \]

140° 45′ adds the declination, which would be correct for an easterly declination. 130° 45′ is a slip in the minutes, and 135° 30′ ignores declination.

Discuss in Forum

The vertical angle between longitudinal axis of a freely suspended magnetic needle and a horizontal line at its pivot, is known as:

A.declination
B.azimuth
C.dip
D.bearing

Exam Year(s)

RSMSSB JE - 2025, RSMSSB - 2025,

Answer: C

The angle is called the dip.

A freely suspended magnetic needle aligns with the Earth's magnetic field, which is inclined to the horizontal everywhere except at the magnetic equator. The vertical angle between the needle and the horizontal is the dip or inclination; it is zero at the magnetic equator and 90° at the magnetic poles. Compass needles carry a small rider to counteract it.

Declination is the horizontal angle between the magnetic and true meridians. Azimuth and bearing are horizontal directions of a line, not vertical angles.

Discuss in Forum

If Fore bearing of a line is S 49°52'E (assuming there is no local attraction), the back bearing of the line will be :

A.N 49°52'W
B.S 52°49'E
C.S 49°52'E
D.N 49°08'E

Exam Year(s)

RSMSSB JE - 2025, RSMSSB - 2025,

Answer: A

The back bearing is N 49°52'W.

In the quadrantal (reduced bearing) system, the back bearing has the same angle as the fore bearing with both letters reversed: N becomes S and E becomes W, and the other way round. So S 49°52'E becomes N 49°52'W, with no local attraction to correct for.

S 49°52'E is the fore bearing repeated, S 52°49'E swaps the degrees and minutes, and N 49°08'E changes the angle and reverses only one letter.

Discuss in Forum

Loading…

Topics

Other Subjects

Tags: Compass Surveying Questions and Answers || Compass Surveying MCQ Questions and Answers || Compass Surveying GK Questions and Answers || Compass Surveying GK MCQ Questions || Compass Surveying Multiple Choice Questions and Answers || Compass Surveying GK || GK on Compass Surveying || Surveying Questions and Answers || Surveying MCQ Questions and Answers || Surveying GK Questions and Answers || GK on Surveying

Compass Surveying Questions and Answers

Topics

Other Subjects

About Us

Stay informed about all important Dates & Notifications