Learn

Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceSingle correctMediumConceptual

JEE Main 31 August 2021, Shift 1, Physics Q13

Question 13 of 90 in this shift, Physics question 13 of 30, Section A.

Which of the following equations is dimensionally incorrect ? Where t = time, h = height, s = surface tension, θ\theta = angle, ρ\rho = density, a, r = radius, g = acceleration due to gravity, v = volume, p = pressure, W = work done, Γ\Gamma = torque, ϵ\epsilon = permittivity, E = electric field, J = current density, L = length.
  1. (1)h=2scos⁡θρrgh = \frac{2s\cos\theta}{\rho rg}
  2. (2)v=πpa48ηLv = \frac{\pi pa^4}{8\eta L}Official answer
  3. (3)W=ΓθW = \Gamma\theta
  4. (4)J=ϵ∂E∂tJ = \epsilon\frac{\partial E}{\partial t}

Official answer

Option 2

NTA final key.

Chapter
Units and Measurements
Topic
No close match in our taxonomy
Idea tested
No close match in our taxonomy

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.