An air column 10cm in length is trapped into the sea end of a capillary tube by a 15cm column of mercury with the tube held vertically as shown above. On inverting the tube the air column becomes 15cm long. The atmospheric pressure during the experiment is
Attached Figure / Diagram
A
90cm
B
76cm
C
75cm
D
60cm
E
50cm
Verified Correct Answer: C.
Physical Principles & Numerical Solution
Let X represent the atmospheric pressure
with tube upright,P1 = ( x + 15)cm, L1 = 10cm
with tube inverted P2 = ( x - 15)cm, L2 = 15cm
using Boyle's law i.e P1V1 = P2V2
(x + 15)10 = (x - 15)15 = 10x + 150 = 15x - 225
15x - 10x = 150 + 225
5x = 375
x = \(\frac{375}{5}\)
= 75cm
Source: Myschool Past Questions Archive (Record #41598)