Abstract: The accurate measurement of the liquid viscosity is quite important in the teaching of physics and industrial application. However, there is an obvious drawback in the traditional measuring skill. We can not catch the iron ball so easily. In this paper, we design a new kind of apparatus at a low cost which can improve the capturing rate up to 90 percent. This new designed instrument works quite well when it is applied to the measurement of the liquid viscosity.

Key words: measurement of liquid viscosity with falling-ball method, broadening light source, receiving circuit, capturing rate