The dimension of surface tension is :

A mercury manometer is used to measure the static pressure at a point in a water pipe as shown in Fig. The level difference of mercury in the two limbs is $$10$$ $$mm.$$ The gauge pressure at that point is

For a given heat flow and for the same thickness, the temp drop across the material will be maximum for

For a current carrying wire of $$20$$ $$mm$$ diameter and having $$k=0.5W/mK$$ is exposed to air $$\left( {h = 20W/{m^2}K} \right),$$ maximum heat dissiption occurs when thickness of insulation is