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Friday, 9 October

JEE Main 2024 · PhysicsNumerical answerNumerical valueMediumData or graph

JEE Main 30 January 2024, Shift 2, Physics Q59

Question 59 of 90 in this shift, Physics question 29 of 30, Section B.

In an experiment to measure the focal length (ff) of a convex lens, the magnitude of object distance (xx) and the image distance (yy) are measured with reference to the focal point of the lens. The yy-xx plot is shown in figure. The focal length of the lens is ________ cmcm.

The figure, in words

Graph of y (cm, vertical, ticks 10-40) vs x (cm, horizontal, ticks 10-40): a descending curve through plotted points A, B, C, D, E (A near x=20,y~35; B near x=20,y~28; C near x=22,y~22; D and E further right near y~10 where the curve flattens); dashed guide lines from the axes to point C.

Official answer

20

NTA final key.

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

Same topic in other shifts

All Lens Maker's Formula questions
  1. 2 Apr 2026, Shift 2 · Q49If sunlight is focused on a paper using convex lens, it starts burning the paper in shortest time when the lens is kept at 30 cm above the…EasyNumerical value
  2. 4 Apr 2026, Shift 2 · Q41A convex lens is made from glass material having refractive index of 1.4 with same radius of curvature on both sides. The ratio of its…EasySingle correct
  3. 5 Apr 2026, Shift 2 · Q40A thin convex lens and a thin concave lens are kept in contact and are co-axial. Which of the following statements is correct for this…EasySingle correct
  4. 5 Apr 2026, Shift 2 · Q41An object ABAB is placed 15 cm on the left of a convex lens PP of focal length 10 cm. Another convex lens QQ is now placed 15 cm right…MediumSingle correct
  5. 8 Apr 2026, Shift 2 · Q30A thin biconvex lens is prepared from the glass (μ=1.5\mu = 1.5) both curved surfaces of which have equal radii of 20 cm each. Left side…MediumSingle correct
  6. 2 Apr 2025, Shift 1 · Q41A slanted object AB is placed on one side of convex lens as shown in the diagram. The image is formed on the opposite side. Angle made by…HardDiagram 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 42 of the 174 JEE Main shifts held from 2017 to 2026.