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Saturday, 31 October

JEE Main 2020 · PhysicsMultiple choiceDiagram basedHardMulti-step

JEE Main 8 January 2020, Shift 2, Physics Q14

Question 14 of 75 in this shift, Physics question 14 of 25, Section A.

As shown in the figure, a battery of emf ϵ\epsilon is connected to an inductor L and resistance R in series. The switch is closed at t=0. The total charge that flows from the battery, between t=0 and t=tct=t_c (tct_c is the time constant of the circuit) is :

The figure, in words

Series circuit in a rectangle: an inductor (coil symbol) labelled L and a resistor (zigzag) labelled R along the top; along the bottom a battery labelled epsilon (emf) on the left and a switch labelled S on the right.
  1. (1)ϵLeR2\frac{\epsilon L}{eR^2}Official answer
  2. (2)ϵReL2\frac{\epsilon R}{eL^2}
  3. (3)ϵLR2\frac{\epsilon L}{R^2}
  4. (4)ϵLR2(1−1e)\frac{\epsilon L}{R^2}\left(1-\frac{1}{e}\right)

Official answer

Option 1

NTA final key (Jan 2020).

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. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.