Module 2 : Electrostatics
Lecture 11 : Capacitance
 

Example 19:
Calculate the voltage across the 5 $\mu$F capacitor in the following circuit.

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Solution :
The equivalent circuit is shown above.The two 10 $\mu F$ capacitors in series is equivalent to a 5 $\mu F$ capacitor.5 $\mu F$ in parallel with this equivalent capacitor gives 10 $\mu F$ as the next equivalent.The circuit therefore consists of a 10 $\mu F$ in series with the 20 $\mu F$ capacitor. Since charge remains constant in a series combination, the potential drop across the 10 $\mu F$ capacitor is twice as much as that across 20 $\mu F$ capacitor. The voltage drop across the 10 $\mu F$(and hence across the given 5 $\mu F$) is $(2/3)\times 12 = 8$V.

 

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