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Derive the expression for the current flowing in an ideal capacitorand its reactance when connected to an ac source of voltageV=V0sinωt​

Answer»

To derive:

The expression for the CURRENT flowing in an ideal capacitor and its reactance when connected to an ac SOURCE of VOLTAGE V=V_(0)sinωt

Derivation:

Let's consider that a capacitor C has been connected to an alternating current source.

So, the CHARGE developed in the capacitor will be:

\sf \therefore \: q = C \times V

\sf \implies \: q = C \times V_{0} \sin( \omega t)

\sf \implies \: q = C  V_{0} \sin( \omega t)

Now, current passing through the circuit :

\sf \therefore \: i =  \dfrac{dq}{dt}

\sf \implies \: i=  \dfrac{d \bigg \{C  V_{0} \sin( \omega t) \bigg \} }{dt}

\sf \implies \: i= CV_{0} \times  \dfrac{d \bigg \{ \sin( \omega t) \bigg \} }{dt}

\sf \implies \: i= CV_{0} \omega \times  \cos( \omega t)

\sf \implies \: i= CV_{0} \omega \times  \sin( \omega t +  \dfrac{\pi}{2} )

\boxed{ \bf\implies \: i= \dfrac{V_{0}}{ (\frac{1}{ \omega C} )} \times  \sin( \omega t +  \dfrac{\pi}{2} ) }

If , we denote the reactance by X_(C):

\boxed{ \bf\implies \: i= \dfrac{V_{0}}{X_{C} } \times  \sin( \omega t +  \dfrac{\pi}{2} ) }

Hence, reactance is :

\boxed{ \bf \therefore \: X_{C} =   \dfrac{1}{ \omega C} }

Hope It HELPS.



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