Question

the angle of contact of mercury is 135° with the glass surface.A narrow tube of glass having diameter 2mm is dipped in a beaker containing mercury.By what height does the mercury go down in the tube relative to the level of mercury outside?​

Answer 1

Answer:

Explanation:

Angle of contact between mercury and soda lime glass, θ=140  

o

 

Radius of the narrow tube, r=1mm=1×10  

−3

m  

Surface tension of mercury at the given temperature, s=0.465Nm  

−1

 

Density of mercury, ρ=13.6×10  

3

kg/m  

3

 

Dip in the height of mercury =h

Acceleration due to gravity, g=9.8m/s  

2

 

Surface tension is related with the angle of contact and the dip in the height as:

s=hρgr/2cosθ

∴h=2scosθ/ρgr

       =2×0.465×cos140  

o

/(1×10  

−3

×13.6×10  

3

×9.8)

       =−0.00534m

       =−5.34m

Here, the negative sign shows the decreasing level of mercury. Hence, the mercury level dips by 5.34 mm.

Answer 2

Answer:angle of contact =135

diameter (d)=2mm=2÷1000=2×10^-3

radius (r)=1×10^-3

Height (h)=?

Now,

h=T2cos135/1×10^-3×13.69×10^-3×10

 h = -5.7m

Explanation: