SSC JE 2019-20: Surveying Quiz-5

The following bearings were observed in an open traverse. Which of the stations are suspected of local attraction?

Which of the following minerals causes local attraction?

i. Bentonite

ii. Dolomite

iii. Ferrite

iv. Magnetite

Assertion (A): If the difference between the fore bearing and back bearing of a line between two stations is less than 180°, it means that at least one station has local attraction.

Reason (R): In case of local attraction at one station, the difference between the fore bearing and back bearing of the line is less than 180°.

Which one of the following is a cause of avoidable local attraction at a station?

i. High tension electric wire

ii. Reinforcement in concrete column

iii. Steel tape in the vicinity

Statement 1: A magnetic needle suspended freely might not be aligned with the magnetic north.

Statement 2: Magnetic needle deviates from its path due to presence of magnetic substances nearby known as local attraction.

Choose the station affected by local attraction from the following:

Which of these statements is wrong?

The following table gives the fore bearings and back bearings in a triangular closed traverse. Find out the corrected fore bearing of CA.

Diurnal declination is