Viscosity Apparatus Stokes Method
Product Code : EL-EAST-10421
Quick answer: The Viscosity Apparatus Stokes Method determines the coefficient of viscosity of a liquid by timing steel balls falling at terminal velocity. A one-metre borosilicate glass tube stands vertically between two upright bars on a heavy cast iron base, with six steel balls of different diameters. Lab Exports manufactures it in Delhi for schools, colleges and universities.
Specifications
| Item | Specification |
|---|---|
| Tube | Borosilicate glass, 1 metre long |
| Base | Heavy cast iron, with two upright bars and clamps |
| Tube closure | Rubber cork without holes at the lower end |
| Steel balls | 6, of different diameters |
| Index marks | 2 rubber bands |
| Lead shot | Not included |
The tube diameter of the current version can be confirmed with [email protected].
How the Stokes' law experiment is done
A small sphere falling through a viscous liquid speeds up until the viscous drag and the upthrust together balance its weight, after which it falls at a steady terminal velocity v. Stokes' law gives the drag on a sphere of radius r as F = 6 pi eta r v. Balancing the forces leads to eta = 2 r^2 (rho - sigma) g/(9 v), where rho is the density of the steel ball and sigma the density of the liquid.
The two rubber bands mark a measured distance on the lower part of the tube, well below the surface, so the ball has reached terminal velocity before timing starts. Using six balls of different diameters lets students check that v is proportional to r^2, as the formula predicts.
- Close the lower end of the tube with the rubber cork, clamp it vertically between the upright bars and fill it with the test liquid, such as glycerine.
- Place the two rubber bands a measured distance apart on the lower half of the tube.
- Measure the diameter of each steel ball with a screw gauge and wet it with the liquid.
- Drop a ball gently along the axis of the tube and time its passage between the bands.
- Repeat for all six balls, plot v against r^2 and calculate eta from the slope.
Key features
- One-metre borosilicate glass tube gives a long, clear fall path
- Heavy cast iron base with two upright bars and clamps holds the tube vertical
- Six steel balls of different diameters for terminal velocity comparisons
- Rubber band index marks can be moved to set the timing distance
- Rubber cork seals the lower end of the tube
Documentation and supply
Most Lab Exports products carry a one-year manufacturer warranty.
Lab Exports manufactures the Stokes' method viscosity apparatus at its works in Laxmi Nagar, Delhi, and supplies it to schools, colleges and universities in India and 60+ countries, handling the export documents for each shipment. More about the company is on the About Lab Exports page.
Related Elasticity and Surface Tension products
- Surface Tension Apparatus (EL-EAST-10420)
- Viscometer Searle's Pattern (EL-EAST-10422)
- Searle's Surface Tension Balance (EL-EAST-10419)
- Quincke's Surface Tension Apparatus (EL-EAST-10418)
- Rising Table with Capillary Tube Clamp (EL-EAST-10417)
- Capillary Tube Clamp (EL-EAST-10416)
The full range is in the Elasticity and Surface Tension section of the Physics Lab range.
Frequently asked questions
How many steel balls are supplied with the Stokes' method apparatus?
Six, each of a different diameter.
Why are rubber bands used as index marks?
They mark the start and end of the timed distance and can be moved along the tube, so timing begins only after the ball has reached terminal velocity.
Is lead shot included?
No, the apparatus is supplied without lead shot.
What is the price of the Stokes' method viscosity apparatus?
Prices are not published on the website. Add the Stokes' method viscosity apparatus to the Enquiry Cart with the Add To Cart button on this page, or email [email protected] with the house code EL-EAST-10421 and the quantity, to receive a quotation.
Does Lab Exports manufacture the Stokes' method viscosity apparatus?
Yes. Lab Exports manufactures the Stokes' method viscosity apparatus at its works at 11/315, Lalita Park, Laxmi Nagar, Delhi 110092, under house code EL-EAST-10421.
Request a quote
Email [email protected] with the house code EL-EAST-10421 and the quantity, or add the Stokes' method viscosity apparatus to the Enquiry Cart with the Add To Cart button on this page. Tender buyers can also see the Tenders and OEM page.
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