Viscosity Apparatus – Stokes’ Method is a physics laboratory apparatus used to determine the coefficient of viscosity of liquids such as glycerine or castor oil by observing the motion of falling steel spheres. It helps students understand Stokes’ law, terminal velocity, viscous drag, and the working principle of a falling sphere viscometer.

The apparatus consists of a transparent tube of approximately 34 mm diameter and 100 cm length, marked with an easy-to-read measuring scale for accurate observation. The tube is supported vertically in a cup placed at the center of a heavy cast iron base and held firmly between three upright rods. A triangular top plate with a Bakelite disc is provided for inserting steel balls into the tube, and the central hole can be closed with a cork to prevent unwanted particles from entering.
 
The lower end of the tube is sealed, and the complete setup provides a stable arrangement for viscosity experiments. Supplied without glycerine, castor oil, and steel balls.

Experimental Objectives

To determine the coefficient of viscosity of a liquid using Stokes’ method.
To study the motion of a spherical body falling through a viscous liquid.
To determine the terminal velocity of steel balls in a liquid medium.
To verify Stokes’ law for viscous drag.
To understand the relationship between viscosity, radius of sphere, density, and terminal velocity.