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A resistance of `20 Omega` is connected to a source of an alternating potential `V=220 sin (100 pi t)`. The time taken by the current to change from the peak value to rms value isA. `0.2 s`B. `0.25s`C. `25 s`D. `2.5 xx 10^(-3)s` |
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Answer» Correct Answer - D Both B and I are is same phase. So, let us calculate the time taken by the voltage to change from peak value of rms value. Now, `220=220 sin 100 pi t_(1)` or `100 pit_(1)=(pi)/(2) or t_(1)=1/(200)s` Again, `(200)/(sqrt(2))=200 sin 100 pit_(2)` or, `1/sqrt(2)=sin 100 pi t_(2) or 100 pi t_(2)=(pi)/(4)` or `t_(2)=1/400 s` Required time `=t_(1)-t_(2)` `=1/200 - 1/400 =(2-1)/(400) = (1)/(400)s=2.5 xx 10^(-3)s`. |
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