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A capacitor of an unknown capacitance is connected to a battery of \mathrm{V} volts. Charge stored inside the capacitor is 720 \mu \mathrm{C}. When the potential across the capacitor is reduced by 240 \mathrm{~V}, the charge stored becomes 240 \mu \mathrm{C}. Determine the charge stored inside the capacitor, if voltage applied gains an increment of 240 \mathrm{~V}.

Option: 1

1200 \mu \mathrm{C}


Option: 2

2400 \mu \mathrm{C}


Option: 3

3600 \mu \mathrm{C}


Option: 4

7200 \mu C


Answers (1)

best_answer

Initial charge =720 \mu \mathrm{C}

Q_1=C V_1                                           .........(1)

Changed potential,

V_2=V-240

Q_2=240 \mu C

Q_2=C V_2                                      ............(2)  

Dividing (1) by (2) -

\frac{Q_1}{Q_2}=\frac{V_1}{V_2}

\frac{720}{240}=\frac{V}{V-240}

V=360 \mathrm{~V}

C=\frac{Q_1}{V_1}=2 \times 10^{-6} F

New voltage =360+240=600 \mathrm{~V}

Charge =C V(\text { new })

\begin{aligned} & =2 \times 10^{-6} \times 600 C \\ = & 1200 \mu C \end{aligned}

Posted by

Sanket Gandhi

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