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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceSingle correctEasyCalculation

JEE Main 26 August 2021, Shift 1, Physics Q6

Question 6 of 90 in this shift, Physics question 6 of 30, Section A.

Two narrow bores of diameter 5.0 mm and 8.0 mm are joined together to form a U-shaped tube open at both ends. If this U-tube contains water, what is the difference in the level of two limbs of the tube. [Take surface tension of water T=7.3×10−2 Nm−1T=7.3\times10^{-2}\ \mathrm{Nm^{-1}}, angle of contact=0, g=10 ms−2g=10\ \mathrm{ms^{-2}} and density of water=1.0×103 kg m−31.0\times10^{3}\ \mathrm{kg\ m^{-3}}]
  1. (1)5.34 mm
  2. (2)3.62 mm
  3. (3)4.97 mm
  4. (4)2.19 mmOfficial answer

Official answer

Option 4

NTA final key.

Chapter
Mechanical Properties of Fluids
Topic
Surface Tension
Idea tested
Capillary Difference in a U-Tube

Same topic in other shifts

All Surface Tension questions
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  3. 4 Apr 2026, Shift 1 · Q47The surface tension of a soap solution is 3.5×10−23.5\times10^{-2} N/m. The work required to increase the radius of a soap bubble from 11 cm to…MediumNumerical value
  4. 5 Apr 2026, Shift 2 · Q33Eight mercury drops, each of radius rr, coalesce to form a bigger drop. The surface energy released in this process is __________. (S is…EasySingle correct
  5. 2 Apr 2025, Shift 2 · Q31Two water drops each of radius rr coalesce to form a bigger drop. If TT is the surface tension, the surface energy released in this…EasySingle correct
  6. 3 Apr 2025, Shift 2 · Q47The excess pressure inside a soap bubble A in air is half the excess pressure inside another soap bubble B in air. If the volume of the…EasyNumerical value

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.