Alternating Current

JEE Main level, single correct, medium

122 of 190

Question 122 of 190

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

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Answer: (B) 5E18,10E33\dfrac{5E}{18},\dfrac{10E}{33}

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\parallel 5\right)+\left(4\parallel 1\right)=\dfrac{33}{10}; (∥⇒\parallel \Rightarrow parallel)
i2=E33/10=10E33{i}_{2}=\dfrac{E}{33/10}=\dfrac{10E}{33}

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