A glass tube of small diameter (d) is dipped in fluid. The height of rise or fall in the tube given by (where w = Specific weight of liquid, $$\alpha $$ = Angle of contact of the liquid surface and $$\sigma $$ = Surface tension)

A. $$\frac{{4{\text{wd}}}}{{\sigma \cos \alpha }}$$

B. $$\frac{{\sigma \cos \alpha }}{{4{\text{wd}}}}$$

C. $$\frac{{4\sigma \cos \alpha }}{{{\text{wd}}}}$$

D. $$\frac{{{\text{wd}}}}{{4\sigma \cos \alpha }}$$

Answer: Option C