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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceDiagram basedMediumDiagram reading

JEE Main 25 February 2021, Shift 2, Physics Q9

Question 9 of 90 in this shift, Physics question 9 of 30, Section A.

A charge ‘q’ is placed at one corner of a cube as shown in figure. The flux of electrostatic field E⃗\vec{E} through the shaded area is :

The figure, in words

A cube drawn in perspective with X, Y, Z axes marked (Z up, Y to the right, X toward lower left). Charge q is marked at the bottom corner nearest the origin of the axes. Two triangular regions are shaded: one on the top face (a triangle with vertices at two top corners and the top corner above the origin-side) and one on the right side face (a triangle running from the top-right corner down to the bottom edge).
  1. (1)q48ε0\frac{q}{48\varepsilon_0}
  2. (2)q4ε0\frac{q}{4\varepsilon_0}
  3. (3)q8ε0\frac{q}{8\varepsilon_0}
  4. (4)q24ε0\frac{q}{24\varepsilon_0}Official answer

Official answer

Option 4

NTA final key.

Chapter
Electric Charges and Fields
Topic
Gauss's Law
Idea tested
Flux via Cube Symmetry

Same idea in other shifts

Asked 3× in all
  1. 4 Apr 2024, Shift 2 · Q41A charge qq is placed at the center of one of the surface of a cube. The flux linked with the cube is:MediumSingle correct
  2. 24 Feb 2021, Shift 2 · Q26A point charge of +12 μC+12\ \mu\mathrm{C} is at a distance 6 cm vertically above the centre of a square of side 12 cm as shown in figure. The…MediumNumerical valueHas a figure

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. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.