Question

In a J tube partially filled with mercury the volume of an air column 4.2 ml and the mercury level in two limbs is same. Some mercury is now added to the tube so that the volume of the air is enclosed in shorter limb is now 2.8 ml.What is the difference in the levels of mercury in this situation (atm pressure=1bar.)

Answer 1

P₁= 1bar= 750.12 mmHg 

P₂ = ( P1 ₊ h) 

 V₁=4.2mL ,V₂ =2.8mL 

 P₁V₁= P₂ V₂ 

or P₂ = P₁V₁/ V₂ 

 = 750.12 x4.2 /2.8 =1125.18 mmHg 

Now 1125.18 = 750.12 ₊ h 

 h = 1125.18 -750.12 

= 375.06 mmHg or 37.506 cm.