Capillary rise
"Capillary rise" is a free, interactive Class 11 Physics simulation for NEET and JEE, built on the NCERT section "Capillary rise" in Mechanical Properties of Fluids. Tubes of different radius dipped in water or mercury: meniscus shape from contact angle, rise or depression h = 2S cos θ/(ρga), and mass lifted ∝ radius. NEET has asked about this idea 2 times in 10 years of papers. JEE Main asked 39 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
From the lesson Capillary rise in Mechanical Properties of Fluids. Change the values and watch what happens.
What it shows
NCERT §9.6.5
Tubes of different radius dipped in water or mercury: meniscus shape from contact angle, rise or depression h = 2S cos θ/(ρga), and mass lifted ∝ radius.
Controls
4 to try
- Slidertube radius 0.1–2 mm
- Togglewater / mercury / custom θ
- Slidersurface tension
- Toggletube length shorter than h
Try this
Choose the radius so water rises exactly 3 cm, then switch to mercury and read the depression.
Common mistake
Using the diameter for a; expecting a short tube to overflow.
In NEET
10 years of papers
Asked 2 times in 10 years of NEET.
See the past questions: Surface Tension, Mechanical Properties of Fluids (chapter)
In JEE Main
42 shifts analysed
39 questions from Mechanical Properties of Fluids across the 42 JEE Main shifts Lumi has analysed (2017–2026).
The idea behind it
NCERT §9.6.5
- Water climbs a narrow tube against gravity; capilla is Latin for hair, and the thinner the tube the higher the climb.
- Water meets glass at an acute angle, so the water surface in a capillary of radius a is concave. The surface is part of a sphere of radius r = a sec θ, giving a pressure difference 2S/r = (2S/a) cos θ across it.
- The water just below the meniscus is therefore below atmospheric pressure. Points A (inside the tube, level with the outer surface) and B (on the outer surface) must be at equal pressure, which lifts a column of height h.
- hρg = 2S cos θ / a, so h = 2S cos θ/(ρga). The rise comes from surface tension and is larger for a narrower tube, typically a few cm for fine capillaries.
- Water in a tube of radius a = 0.05 cm with S = 0.073 N m⁻¹ (θ taken as 0): h = 2 × 0.073/(10³ × 9.8 × 5 × 10⁻⁴) = 2.98 × 10⁻² m = 2.98 cm.
- If the meniscus is convex, as for mercury in glass, cos θ is negative and the liquid stands lower inside the capillary than outside: capillary depression.
Questions
5 answers
- What does the "Capillary rise" simulation show?
- Tubes of different radius dipped in water or mercury: meniscus shape from contact angle, rise or depression h = 2S cos θ/(ρga), and mass lifted ∝ radius.
- What mistake does the "Capillary rise" simulation fix?
- A common mistake it clears up: using the diameter for a; expecting a short tube to overflow.
- Has NEET asked about this idea?
- Yes. NEET has asked about this idea 2 times in 10 years of papers.
- Does JEE Main ask questions from Mechanical Properties of Fluids?
- Yes. JEE Main asked 39 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
- Is this simulation free?
- Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Capillary rise" in Mechanical Properties of Fluids (Class 11 Physics).
Embed this simulation
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