Searle's Surface Tension Balance

Product Code : EL-EAST-10419

Specifications

How the balance is used

The balance works on the torsion principle. A light beam is carried on a stretched wire, so a vertical force at one end of the beam twists the wire and the beam turns through an angle proportional to that force. Surface tension provides the force: when a thin plate or wire frame hung from the beam touches a liquid surface or holds a soap film, the surface pulls it down with a force F = 2 T L, where L is the length of the edge in contact and the factor 2 accounts for the two surfaces.

The deflection is first calibrated with small known masses, so that the deflection produced by the liquid can be converted into a force and then into surface tension, T = F/(2L). Because the method measures a force directly rather than a capillary height, it suits soap films and transparent liquids alike.

1. Set the tripod stand on a firm bench and level it with the levelling screw.
2. Calibrate the beam by noting its deflection for several small known masses.
3. Bring the liquid surface, or the soap film, into contact with the plate or frame hung from the beam.
4. Record the deflection, convert it to a force with the calibration, and calculate T.

Key features

• Torsion-balance principle measures surface tension as a direct force
• Beam carried on a stretched wire for a sensitive, proportional response
• Suitable for soap films as well as transparent liquids
• Tripod stand with levelling screw for a stable, level set-up
• A force-based method to compare with capillary rise results

Documentation and supply

Most Lab Exports products carry a one-year manufacturer warranty.

Lab Exports manufactures the Searle's surface tension balance 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

• Quincke's Surface Tension Apparatus (EL-EAST-10418)
• Surface Tension Apparatus (EL-EAST-10420)
• Rising Table with Capillary Tube Clamp (EL-EAST-10417)
• Viscosity Apparatus Stokes Method (EL-EAST-10421)
• Capillary Tube Clamp (EL-EAST-10416)
• Viscometer Searle's Pattern (EL-EAST-10422)

The full range is in the Elasticity and Surface Tension section of the Physics Lab range.

Frequently asked questions

How does Searle's surface tension balance measure surface tension?

By the deflection of a beam carried on a stretched wire. The pull of the liquid surface twists the wire, and the calibrated deflection gives the force and hence the surface tension.

Which liquids can be tested?

Soap film or any transparent liquid.

How is it different from the capillary rise method?

It measures the pulling force of the surface directly with a torsion balance, instead of the height a liquid rises in a capillary tube.

What is the price of the Searle's surface tension balance?

Prices are not published on the website. Add the Searle's surface tension balance to the Enquiry Cart with the Add To Cart button on this page, or email [email protected] with the house code EL-EAST-10419 and the quantity, to receive a quotation.

Does Lab Exports manufacture the Searle's surface tension balance?

Yes. Lab Exports manufactures the Searle's surface tension balance at its works at 11/315, Lalita Park, Laxmi Nagar, Delhi 110092, under house code EL-EAST-10419.

Request a quote

Email [email protected] with the house code EL-EAST-10419 and the quantity, or add the Searle's surface tension balance to the Enquiry Cart with the Add To Cart button on this page. Tender buyers can also see the Tenders and OEM page.