Physics Lab Equipment

LEMI-32 Measuring Liquid Viscosity - Falling Ball Method

LEMI-32 Measuring Liquid Viscosity - Falling Ball Method


  • Photoelectric timing

  • High accuracy

  • Ideal for for fluid mechanics teaching


Viscosity coefficient is one of the important properties of liquid. Measurement of liquid viscosity coefficient using a falling ball can reveal related physical phenomena clearly. Normally, the measurement accuracy of the falling ball method is not high by using a manual stopwatch considering the existing parallax errors of the ball.


This apparatus is designed with the following benefits:


1. Using photoelectric sensor and electronic timer to avoid the parallax and timing errors caused by a stopwatch

2. Improved mechanical design to ensure precise falling trace of the ball

3. Using laser ranging to accurately measure both the fall time and fall distance to avoid the parallax error


Using this apparatus, the following experiments can be conducted:


1. Measure the viscosity coefficient of a liquid using falling ball method

2. Use a photoelectric sensor for timing experiment

3. Use a stopwatch to time a falling ball, and compare results with the photoelectric timing method

The instruction manual contains experimental configurations, principles, step-by-step instructions, and examples of experiment results. Please click Experiment Theory and Contents to find more information about this apparatus.

Main Specifications

Electronic timerDisplacement range: 400 mm; resolution: 1 mm
Timing range: 250 s; resolution: 0.1 s
Measuring cylinderVolume: 1000 mL; height: 400 mm
Measurement error<3%

Part List 

Stand Rack1
Main Machine1
Laser Emitter2
Laser Receiver2
Connection Wire1
Measuring Cylinder1
Small Steel Ballsdiameter: 1.5, 2.0 and 2.5 mm, 20 each
Magnet Steel1
Power Cord1

LEMI-32 Measuring Liquid Viscosity - Falling Sphere Method.png

1. Guide tube

2. Laser emitter A

3. Laser emitter B

4. Laser receiver A

5. Laser receiver B

6. Measuring cylinder

7. Back panel

8. Power socket

9. Laser control

10. Front panel

11. Timer

12. Power switch

13. Timer reset

Schematic of apparatus

 LEMI-32 Measuring Liquid Viscosity - Falling Sphere Method.png

Viscosity of castor oil

(Click graph to enlarge)

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