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Saturday, 31 October

JEE Main 2020 · PhysicsMultiple choiceDiagram basedMediumData or graph

JEE Main 5 September 2020, Shift 1, Physics Q17

Question 17 of 75 in this shift, Physics question 17 of 25.

For a concave lens of focal length ff, the relation between object and image distances u and vv, respectively, from its pole can best be represented by (u = vv is the reference line) :

The figure, in words

Each option is a graph with v on the vertical axis and u on the horizontal axis; tick f marked on both axes; line labelled u=v; dashed horizontal line at v = f.
  1. (1)[figure: graph of v (vertical) against u (horizontal); straight line labelled u=v through the origin; dashed horizontal line at v = f; curve rises from the origin above the line and meets the line at u = f at the dashed level, then runs along the dashed level]
  2. (2)[figure: graph of v against u; straight line labelled u=v through the origin; dashed horizontal line at v = f; curve rises from the origin slightly above the line, crosses the line below u = f, then stays below it and approaches the dashed level]
  3. (3)[figure: graph of v against u; straight line labelled u=v through the origin; dashed horizontal line at v = f; curve rises steeply from the origin above the dashed level to a hump, then comes down to cross the line at the dashed level and runs along it]
  4. (4)[figure: graph of v against u; straight line labelled u=v through the origin; dashed horizontal line at v = f; curve rises from the origin staying below the line throughout and approaches the dashed level]Official answer

Official answer

Option 4

NTA final key (Sep 2020).

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. 4 Aug 2021, Shift 2 · Q4The reported graph shows the variation of ‘v’ with ‘u’, where ‘u’ represents the distance of the object from the lens and v represent the…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.