Abstract: An instrument for measuring the viscosity of a liquid is designed by using the forced vibration of a spring oscillator.A direct-current motor drives a steel ball to vibrate in the measured liquid.A Hall sensor is used to measure the vibration amplitudes and resonance frequencies of the steel ball.The viscosities of the castor oil and glycerol with the different temperatures are measured by the use of the instrument,respectively.The experimental results show that the relative errors between the measured values and theoretical values of the castor oil and glycerol under the temperatures from 23℃ to 29℃ are less than 3%.This measurement method has advantages of higher accuracy,no oil-pollution,obvious resonance,clear physical principle and good teaching effect.

Key words: measurement of viscosity, spring oscillator, forced vibration