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Experiment: Determination of the surface tension of water by the capillary rise method. Which of the following is the correct complete list of apparatus and materials required?

1. A glass/plastic capillary tube, travelling microscope, beaker, cork fitted with a pin, clamps and stand, thermometer, dilute nitric acid solution, dilute caustic soda solution, water, and a plumb line.
2. A glass capillary tube, vernier calipers, burette, thermometer, water, and a plumb line.
3. A capillary tube, stop-watch, metre scale, beaker, and water.
4. A glass capillary tube, screw gauge, spring balance, ice, and water.

Correct answer: A glass/plastic capillary tube, travelling microscope, beaker, cork fitted with a pin, clamps and stand, thermometer, dilute nitric acid solution, dilute caustic soda solution, water, and a plumb line.

Solution

The standard capillary-rise experiment uses a fine capillary tube, a travelling microscope to read the small rise height and tube radius, a beaker for water, a cork-and-pin to mark the water surface, clamps/stand to hold things vertical, a thermometer to record temperature (surface tension is temperature dependent), dilute nitric acid and caustic soda to clean grease/contaminants from the tube, water as the test liquid, and a plumb line to ensure verticality.

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