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Saturday, 31 October

JEE Main 2025 · PhysicsMultiple choiceSingle correctEasyApplication

JEE Main 8 April 2025, Shift 2, Physics Q38

Question 38 of 75 in this shift, Physics question 13 of 25, Section A.

Two metal spheres of radius R and 3R have same surface charge density σ\sigma. If they are brought in contact and then separated, the surface charge density on smaller and bigger sphere becomes σ1\sigma_1 and σ2\sigma_2, respectively . The ratio σ1σ2\frac{\sigma_1}{\sigma_2} is
  1. (1)9
  2. (2)13\frac{1}{3}
  3. (3)3Official answer
  4. (4)19\frac{1}{9}

Official answer

Option 3

NTA final key.

Chapter
Electric Charges and Fields
Topic
Conductors in Fields
Idea tested
Surface Charge Density Ratio of Connected Spheres

Same idea in other shifts

Asked 2× in all
  1. 26 Jul 2022, Shift 2 · Q35Two uniformly charged spherical conductors AA and BB of radii 5 mm and 10 mm are separated by a distance of 2 cm. If the spheres are…MediumSingle correct

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.