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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceDiagram basedMediumData or graph

JEE Main 4 August 2021, Shift 2, Physics Q4

Question 4 of 90 in this shift, Physics question 4 of 30, Section A.

The reported graph shows the variation of ‘v’ with ‘u’, where ‘u’ represents the distance of the object from the lens and v represent the distance of image from lens. This lens forms a real image of the object. The power of the lens is -

The figure, in words

Graph of |v| in cm (vertical axis, ticks 20, 40, 60, 80) against |u| in cm (horizontal axis, ticks 20, 40, 60, 80): a decreasing curve that starts high at small |u| and falls off; a horizontal line from |v| = 20 on the vertical axis and a vertical line from |u| = 20 on the horizontal axis meet on the curve.
  1. (1)−10-10 D
  2. (2)10 DOfficial answer
  3. (3)−5-5 D
  4. (4)5 D

Official answer

Option 2

NTA final key.

Chapter
Ray Optics and Optical Instruments
Topic
Lens Maker's Formula
Idea tested
v versus u Graph

Same idea in other shifts

Asked 3× in all
  1. 30 Jan 2024, Shift 2 · Q59In an experiment to measure the focal length (ff) of a convex lens, the magnitude of object distance (xx) and the image distance (yy)…MediumNumerical valueHas a figure
  2. 5 Sep 2020, Shift 1 · Q17For a concave lens of focal length ff, the relation between object and image distances u and vv, respectively, from its pole can best be…MediumDiagram basedHas 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.