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Question: Answered & Verified by Expert
An alternating current in a circuit is given by $I=20 \sin (100 \pi t+0.05 \pi)$ A. The r.m.s. value and the frequency of current respectively are
PhysicsAlternating CurrentJEE Main
Options:
  • A $10 \mathrm{A}$ and $100 \mathrm{Hz}$
  • B $10 \mathrm{A}$ and $50 \mathrm{Hz}$
  • C $10 \sqrt{2} \mathrm{A}$ and $50 \mathrm{Hz}$
  • D $10 \sqrt{2}$ A and $100 \mathrm{Hz}$
Solution:
1191 Upvotes Verified Answer
The correct answer is: $10 \sqrt{2} \mathrm{A}$ and $50 \mathrm{Hz}$
Given, $I=20 \sin (100 \pi t+0.05 \pi)$
The root mean square value of alternating
$$
\text { current }=l_{\mathrm{ms}}=\frac{l_{0}}{\sqrt{2}}=\frac{20}{\sqrt{2}}=10 \sqrt{2} \mathrm{A}
$$
Also, $\quad \omega=100 \pi$
$\Rightarrow \quad 2 \pi f=100 \pi$ or $f=50 \mathrm{Hz}$

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