### Mechanics

Principle of capillary method

Schematic of apparatus

## LEMI-35 Measuring Liquid Viscosity - Capillary Method

Features

• Innovative apparatus construction

• Temperature variable and controllable

• Ideal for bio/medical physics teaching

Introduction

In the steady flow of liquid, due to the flow rate difference among layers, there exists an interaction force between two adjacent layers, known as the viscous force. Viscosity is one of the important properties of liquid with a wide range of applications. For example, it is found that many cardiovascular diseases are associated with the change in blood viscosity. The increase of the blood viscosity decreases or slows down the blood flow into organs, causing a variety of cardio-vascular diseases and many other symptoms of physical discomfort. Therefore, measuring blood viscosity can help diagnose human health.

This apparatus is designed to measure the viscous coefficient of liquid using an Ostwald viscometer. It requires a small volume of sample with high precision temperature control and good repeatability. This experimental apparatus can be used for basic physics experiments and research use, and especially for biophysics teaching.

Using this apparatus, the following experimental objectives can be implemented:

1. Understand the Poiseuille law

2. Learn how to measure viscous and surface tension coefficients of liquid using Ostwald viscometer

Specifications

 Description Specifications Temperature controller Range: room temperature to 45 °C; resolution: 0.1 °C Stopwatch Resolution: 0.01 s Motor speed Adjustable, power supply 4 V ~ 11 V Ostwald viscometer Capillary tube: inner diameter 0.55 mm, length 102 mm Beaker volume 1.5 L Pipette 1 mL

Part List

 Description Qty Controller 1 Glass beaker 1 Lid of beaker (W/ heater, sensor, capillary holder & wire sockets) 1 Magnetic rotor 1 Ostwald tube 2 Rubber air pump 1 Connection wire 2 Stopwatch 1 Pipette 1 Manual 1

Principle of capillary method

Schematic of apparatus