Question

The following observations were made to determine sensitivity of two level tubes. Distance of staff from the instrument was 100 m and length of one division is equal to 2 mm.

Bubble tube	Case	Bubble reading	Staff reading
LHS	RHS
A	I	13	5	1.681
II	8	12	1.767
B	I	15	3	1.635
II	6	14	1.788

Which bubble tube is more sensitive:

• A. Both A and B are equally sensitive
• B. B
• C. It can't be determined
• D. A

Answer 1

The correct option is B B

For bubble tube 'A'

${\alpha }_A=\frac{S}{nd}\times 206265$

$\text{n}=\frac{(13-5)+(12-8)}{2}=6$

${\alpha }_A=\frac{1.767-1.681}{6\times 100}\times 206265$

$={29.565}^{\prime \prime }$

For bubble tube 'B'

${\alpha }_B=\frac{S}{nd}\times 206265$

$n=\frac{(15-3)+(14-6)}{2}=10$

${\alpha }_B=\frac{1.788-1.635}{10\times 100}\times 206265$

$={31.559}^{\prime \prime }$
$Since,{\alpha }_A<{\alpha }_B$
Hence bubble tube 'B' is more sensitive