Abstract: An instrument for measuring viscosity coefficient of liquid is developed.A taper magnet is used to hold and release the steel ball,and then the steel ball can fall along the cylinder＇s axis.A bar magnet is used to pick up the falling steel ball and make the steel ball be reused without washing.A measuring cylinder is also specially designed to contain the measured liquid.The starting timing-position of the terminal velocity of the steel ball is theoretically analyzed,and tts numerical calculation is performed by the use of MATLAB software. The experimental results show that this instrument has advantages of high accuracy,no oil-pollution and simple operation.

Key words: instrument for measuring viscosity coefficient of liquid, method of falling ball, magnet