JEE Main 2026 · PhysicsMultiple choiceSingle correctEasyCalculation

JEE Main 4 April 2026, Shift 1, Physics Q44

Question 44 of 75 in this shift, Physics question 19 of 25, Section A.

A telescope with objective diameter

R

is used to observe a distant star emitting light of wavelength

500

nm, at a resolution of

5\times10^{-7}

radian. The value of

R

is ______ cm.

(1) $61$
(2) $122$ Official answer
(3) $244$
(4) $305$

Official answer

Option 2

NTA final key.

Chapter: Wave Optics
Topic: Optical Instruments
Idea tested: Resolving Power

Same topic in other shifts

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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 42 of the 174 JEE Main shifts held from 2017 to 2026.