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Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsElectrostatic Potential and Capacitance3 Marks
Question
  1. Find equivalent capacitance between A and B in the combination given below. Each capacitor is of 2 μF capacitance.

  1. If a dc source of 7 V is connected across AB, how much charge is drawn from the source and what is the energy stored in the network?
✓

Answer

Capacitors  $C_2$, $C_3$ $\text{and}$ $C_4 $$\ \ \text{are in parallel}$

$\therefore C_{234}=C_2+C_3+C_4$

$\therefore C_{234}=6\mu F$

Capacitors $C_1$,$​​​​C_{234}$ $\text{and}$  $C_5$ are in series

$\frac{1}{C_{eq}}=\frac{1}{C_1}+\frac{1}{C_{234}}+\frac{1}{C_5}=\frac{1}{2}+\frac{1}{6}+\frac{1}{2}$

$=\frac{7}{6}\mu F$

$C_{equivalent}=\frac{6}{7}\mu F$

Charge drawn from the source

$Q=C_{eq}V,$

$=\frac{6}{7}\times7\mu C=6\mu C$

Energy stored $U=\frac{Q^2}{2C}$

$=\frac{6\times6\times10^{-12}\times7}{2\times6\times10^{-6}}\text{J}$

$=21\mu \text{J}$.

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