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Current in an ac circuit is given by i = 3 sin \omega t + 4 cos \omega t then :     

Option: 1

rms value of current is 5 A.    


Option: 2

mean value of this current in one half period will be \frac{6}{\pi}


Option: 3

if voltage applied is V = Vm sin \omegat then the circuit must be containing resistance and capacitance.


Option: 4

 if voltage applied is V = Vm sin \omegat, the circuit may contain resistance and inductance.


Answers (1)

best_answer

 

R C Circuit Voltage -

V_{R}=IR

V_{C}={I}X_{C}

- wherein

 

 

R.L Circuit Voltage -

V_{R}= IR

V_{L}= {I}X_{L}

- wherein

 

 

Root mean square i_{rms} -

i_{rms}= \sqrt{\frac{i_{1}^{2}+i_{1}^{2}+----}{\eta }}= \sqrt{\overline{i}^{2}}

\sqrt{\frac{\int_{0}^{T}i^{2}dt}{\int_{0}^{T}dt}}= \frac{{i_{0}}'}{\sqrt{2}}= 0.707\, {i}'_{0}

                                        = 70.7 % {i}'_{0}

- wherein

{i}'_{0} - Peak Current

 

   

i = 3 sin \omega t + 4 cos \omega t

= 5\left [ \frac{3}{5}sin \omega t+\frac{4}{5}\cos \omega t \right ]

= 5\left [ \sin (\omega t +\delta ) \right ]                       ....................(1)

rms value = \frac{5}{\sqrt{2}}\Rightarrow mean value =\frac{\int_{T_{1}}^{T_{2}}idt}{\int_{T_{1}}^{T_{2}}dt}

\therefore Initial value of time is not given hence the mean value will be different for various time intervals.

  If voltage applied is V = Vm sin\omegat then i given by equation (1) indicates that it is ahead of V by \delta where 0 < \delta < 90 which indicates that the circuit contains R & C.

 

 

Posted by

Ajit Kumar Dubey

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