Two narrow bores of diameters 3.0 mm and 6.0 mm are joined together to form a U-tube open at both ends. If the U-tube contains water, what is the difference in its levels in the two limbs of the tube ? Surface tension of water at the temperature of the experiment is `7.3xx 10^-2 N m^-1 '. Take the angle of contact to be zero and density of water to be `1.0xx 10^3 kg m^- 3` (`g = 9.8 m s^-2`) .