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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceSingle correctMediumMulti-step

JEE Main 18 March 2021, Shift 2, Physics Q18

Question 18 of 90 in this shift, Physics question 18 of 30, Section A.

The time taken for the magnetic energy to reach 25% of its maximum value, when a solenoid of resistance R, inductance L is connected to a battery, is :
  1. (1)LRln⁡2\frac{L}{R}\ln 2Official answer
  2. (2)LRln⁡5\frac{L}{R}\ln 5
  3. (3)LRln⁡10\frac{L}{R}\ln 10
  4. (4)infinite

Official answer

Option 1

NTA final key.

Chapter
Electromagnetic Induction
Topic
No close match in our taxonomy
Idea tested
No close match in our taxonomy

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.