The density meters include an oscillating U-tube. This measures the frequency of oscillation in the substance, whether it is a liquid or gas. The user will place the sample into the machine, which then excites the tube using electricity. This causes a change in the oscillation of the tube. From the number received, it becomes possible to calculate the density value of the substance. It is a very effective tool, and it is at work in a wide range of different fields and industries. However, it does take someone who knows and understands density calculation to make the most use out of the machine.