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  • A resistance of is connected to a source of alternating current rated

A resistance of \mathrm{40\, \Omega } is connected to a source of alternating current rated \mathrm{220\, V,50\, Hz }. Find the time taken by the current to change from its maximum value to the \mathrm{rms} value :

Option: 1

\mathrm{2.5\, ms}


Option: 2

\mathrm{1.25\, ms}


Option: 3

\mathrm{2.5\, s}


Option: 4

\mathrm{0.25\, s}


Answers (1)

best_answer

Vrms=220 V
For pure resistive ckt ,
Current and voltage are in the same phase

\mathrm{IF\; V= V_{0}\sin \omega t}
then \mathrm{I= I_{0}\, \sin \omega t}

\mathrm{I= I_{rms}= \frac{I_{0}}{\sqrt{2}}= I_{0}\sin \omega t}
                         \mathrm{\omega t=\frac{\pi}{4}}
                         \mathrm{\Rightarrow t=\frac{T}{8}}



\mathrm{\Delta t= \left ( \frac{T}{4} \right )-t= \frac{T}{8}= \frac{1}{8\times F}= \frac{1}{400}}
       \mathrm{=2.5\, ms}

Time taken to change from its maximum value to rms value is same as time taken to change from rms value to maximum value

\mathrm{\therefore \Delta t= \frac{T}{8}= 2.5\, ms}
The correct option is (1)
      

Posted by

mansi

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