Core TradesQuestion 51 of 700
In differential leveling, a 'backsight' reading is taken on:
a.A point whose elevation is being newly determined
b.The next station ahead in the direction of travel
c.A point of known elevation, such as a benchmark, to set the instrument height
d.The lowest point in the excavation
Explanation
A backsight is read on a point of known elevation (a benchmark or turning point) to establish the height of the instrument. A foresight, by contrast, is read on the new point whose elevation is being found.
Practice all 700 questions free — no signup required.
Related questions on this topic
- At the rake (gable) edge of a shingle roof, the drip edge should be installed:
- In a basic (non-high-wind) zone, standard asphalt shingles are typically fastened with a MINIMUM of how many nails per shingle?
- A simple gable roof covers a building 24 feet by 40 feet in plan. At a 6:12 pitch (slope factor 1.118), what is the approximate total roof surface area?
- A 'balanced' grading design PRIMARILY seeks to:
- Which field method determines in-place soil density by excavating a small hole and replacing the soil with a calibrated sand from a known-volume cone?
- In soil compaction, the maximum dry density of a soil is achieved when it is compacted at its:
Last reviewed: · editorial process
PrepPass Editorial Team · Verified against California CSLB General Building (B) Trade Examination · How we review