A glass capillary tube is of the shape of a truncated cone with an apex angle $\mathrm{\alpha }$ so that its two ends have cross section of different radii. When dipped in water vertically, the water rises in it to a height h, where the radius of its cross-section is b if the surface tension of water is S, its density is $\rho$ , and contact angle with glass is $\theta$ when value of h will be (g is the   acceleration due to gravity) $\mathrm{h}=\frac{\mathrm{kS}}{3\mathrm{\rho gb}}\cos \left(\mathrm{\theta }+\frac{\mathrm{\alpha }}{2}\right)$ then k is