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NEET AIPMT SOLVED PAPER 2001

  • question_answer
                    The reactance of a capacitor of capacitance C is X. If both the frequency and capacitance be doubled, then new reactance will be:                                                                                                                                  

    A)                 X                            

    B)                 2X                          

    C)                 4X                          

    D)                 \[\frac{X}{4}\]

    Correct Answer: D

    Solution :

                    If a capacitor of capacitance C is connected with an AC signal, then reactance of that circuit is purely capacitive.                 The capacitive reactance is                  \[X=\frac{1}{\omega C}=\frac{1}{2\,\pi \,f\,C}(\omega =2\,\pi \,f)\] \[orX\,\,\propto \,\,\frac{1}{f\,C}\] \[\therefore \frac{X'}{X}=\frac{fC}{f'C'}=\frac{f\times C}{2f\times 2C}\] \[or\frac{X'}{X}=\frac{1}{4}\] \[orX'=\frac{X}{4}\]


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