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JEE Main 202125 FebruaryMorning Shift
Exam
JEE Main
Year
2021
Date
25 February
Shift
Morning Shift
Subject
Physics
Chapter
Alternating Current

JEE Main 2021 · 25 February · Morning Shift · Physics · Alternating Current

The current ( i ) at time t = 0 and t = ∞ respectively for the...

The current (i)( i ) at time t=0t = 0 and t=∞t = \infty respectively for the given circuit is :

The current ( i ) at time t = 0 and t = ∞ respectively for the given circuit is :

Options

  1. A5E18,18E55\dfrac{5E}{18}, \dfrac{18E}{55}
  2. B5E18,10E33\dfrac{5E}{18}, \dfrac{10E}{33}
  3. C10E33,5E18\dfrac{10E}{33}, \dfrac{5E}{18}
  4. D18E55,5E18\dfrac{18E}{55}, \dfrac{5E}{18}

Correct answer

B. 5E18,10E33\dfrac{5E}{18}, \dfrac{10E}{33}

Step-by-step solution

At t=0t = 0, current through inductor is zero,

hence Req=(5+1)‖(5+4)=185{R}_{eq} = \left(5 + 1\right) ‖ \left(5 + 4\right) = \dfrac{18}{5}

i1=E18/5=5E18{i}_{1} = \dfrac{E}{18 / 5} = \dfrac{5E}{18}

At t=∞,t = \infty , inductor becomes a simple wire and now the circuit will be as shown in figure

hence Req=(5∥5)+(4∥1)=3310;{R}_{eq} = \left(5 ∥ 5\right) + \left(4 ∥ 1\right) = \dfrac{33}{10}; (∥⇒∥ ⇒ parallel)

i2=E33/10=10E33{i}_{2} = \dfrac{E}{33 / 10} = \dfrac{10E}{33}

The current ( i ) at time t = 0 and t = ∞ respectively for the given circuit is :

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