Physics · Practical apparatus

Liquid expansion capillary

Warm a liquid-filled vessel with a narrow capillary. The observed rise reflects liquid expansion minus vessel expansion, so apparent expansion is smaller than true expansion.

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Liquid expansion capillary

திரவத்தின் தோற்ற விரிவு என்பது அதன் உண்மை விரிவிலிருந்து பாத்திர விரிவை கழித்தது. மெல்லிய குழாய் உயர மாற்றத்தைப் பெரிதாக்கும்.

Key notes, relationships and model limits

Key relationship

ΔVapp=V₀(βliquid−βvessel)ΔT; Δh=ΔVapp/Atube.

Practical tip

Warm a liquid-filled vessel with a narrow capillary. The observed rise reflects liquid expansion minus vessel expansion, so apparent expansion is smaller than true expansion.

Common trap

The vessel expands too. The capillary measures apparent expansion, which uses βliquid − βvessel.

Model limits

constant volume expansion coefficients, uniform temperature and fixed tube area. Tube expansion and anomalous water behaviour excluded.

What you will learn

Adjust liquid expansion capillary apparatus, observe its reading and derive the indicated physical quantity.

Try the experiment

Try both scenarios, change one control, and predict the result before checking the graph and readouts.

Think of it this way

Change one input while keeping the others fixed, as you would in a controlled experiment.

Worked example

For V₀=100 mL, βapp=1.83×10⁻⁴/K and ΔT=20 K, apparent volume rises 0.366 mL.

Why this matters

The model connects liquid expansion capillary with an observable reading. Check the equation and assumptions before applying it.

Before you start

SI units · algebra · graph reading

Check your understanding

Apparent liquid expansion relative to its vessel uses coefficient?

βliquid plus βvessel.
βliquid minus βvessel.
βvessel minus βliquid.

Read the explanation

βliquid minus βvessel.

Course connection: Virtual apparatus preparation. Check exact board/exam membership in the syllabus sources. Physical practical work remains necessary.