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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 25 February 2021, Shift 1, Physics Q16

Question 16 of 90 in this shift, Physics question 16 of 30, Section A.

Magnetic fields at two points on the axis of a circular coil at a distance of 0.05 m and 0.2 m from the centre are in the ratio 8 : 1. The radius of coil is __________.
  1. (1)0.1 mOfficial answer
  2. (2)0.15 m
  3. (3)0.2 m
  4. (4)1.0 m

Official answer

Option 1

NTA final key.

Chapter
Moving Charges and Magnetism
Topic
Biot-Savart Law
Idea tested
Field on axis of circular loop

Same idea in other shifts

Asked 2× in all
  1. 15 Apr 2023, Shift 1 · Q59An election in a hydrogen atom revolves around its nucleus with a speed of 6.76×1066.76 \times 10^6 ms−1^{-1} in an orbit of radius 0.52…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.