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Saturday, 31 October

JEE Main 2026 · PhysicsMultiple choiceSingle correctHardMulti-step

JEE Main 5 April 2026, Shift 1, Physics Q42

Question 42 of 75 in this shift, Physics question 17 of 25, Section A.

A compound microscope is designed with two symmetric biconvex lenses. The objective lens is cut vertically, creating two identical plano-convex lenses. One of them is used in place of original objective lens. To retain same magnification keeping the object distance unchanged, the tube length has to be
  1. (1)increased two timesOfficial answer
  2. (2)increased 32\frac{3}{2} times
  3. (3)decreased two times
  4. (4)decreased 32\frac{3}{2} times

Official answer

Option 1

NTA final key.

Chapter
Ray Optics and Optical Instruments
Topic
Optical Instruments
Idea tested
Microscope Tube Length

Same idea in other shifts

Asked 2× in all
  1. 5 Sep 2020, Shift 1 · Q24A compound microscope consists of an objective lens of focal length 1 cm and an eye piece of focal length 5 cm with a separation of 10 cm.…MediumNumerical value

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.