A resistance of 40 $\Omega$ is connected to a source of alternating current rated 220 V, 50 Hz. Find the time taken by the current to change from its maximum value to the rms value :
Solution
<p>$I = {I_0}\cos (\omega t)$ say</p>
<p>$\Rightarrow$ At maximum $\omega {t_1} = 0$ or ${t_1} = 0$</p>
<p>Then at rms value $I = {I_0}/\sqrt 2$</p>
<p>$\Rightarrow \omega {t_2} = \pi /4$</p>
<p>$\Rightarrow \omega ({t_2} - {t_1}) = \pi /4$</p>
<p>$\Delta t = {\pi \over {4\omega }} = {{\pi T} \over {4 \times 2\pi }}$</p>
<p>$= {1 \over {400}}s$ or 2.5 ms</p>
About this question
Subject: Physics · Chapter: Alternating Current · Topic: AC Circuits: R, L, C
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