Oscillating U-tube

An oscillating U-tube is a device that is used to measure the density of a liquid. It works by having two different liquids – usually water and oil – in two separate U-shaped tubes connected together and sealed at the bottom. As the water and oil settle according to their densities, the heavier liquid (the oil) will move down to the bottom of the U-shaped tubes and the lighter liquid (the water) will float on top. The U-shaped tubes are connected at the bottom and when the liquids settle, the level of the two will be the same. This level is what is measured when the oscillating U-tube is used. When something causes the liquids to move, such as a movement of the air or a vibration of the ground, the U-tube will vibrate and all of the liquid in the U-tube will start to move up and down, back and forth. This motion will cause the levels in the two U-shaped tubes to change, which can be measured and used to calculate the density of the liquid.