Question

Calculate the error in the staff reading on staff at a distance of 100mm due to being out of the center of the bubble by 4 divisions. The sensitivity of the bubble tube is 30 seconds per 2 mm division.

• A. 0.58
• B. 0.34
• C. 0.29
• D. 0.67

Answer 1

The correct option is A 0.58

Data given : Sensitivity, $\varphi =30"$ per 2mm divison

Distance between staff and instrument, L = 100m

Deviation of bubble from center, n= 4

Find, error in staff reading, S =?


$Sensitivity,\varphi =\frac{206265\times S}{L\times n}$

$30=\frac{206265\times S}{100\times 4}$

$S=\frac{30\times 100\times 4}{206265}$

S = 0.058m