Question

In figure, the battery has a potential difference of 20 V. Find the charge (in $\mu C$) on the equivalent capacitance across the battery :

Answer 1

The corresponding equivalent circuits are shown in figure. The net capacitance for top part is $C_t=2+\frac{4\times 4}{4+4}+2=6\mu F$

The net capacitance for bottom part is $C_b=3+3=6\mu F$

Now $C_t,C_b$ are in series.

So, the equivalent capacitance for the circuit is $C_{eq}=\frac{C_t{C}_b}{C_t+C_b}=\frac{6\times 6}{6+6}=3\mu F$

Thus, charge stored on the equivalent capacitance is $Q_{eq}=C_{eq}V=3\times 20=60\mu C$