Question

Figure shows four capacitors connected across a power supply of 310 V. What is the charge and potential difference across the 4$\mu$F capacitor?

• A. 1200 $\mu$F, 310 V
• B. 600 $\mu$F, 310 V
• C. 600 $\mu$F, 150 V
• D. 1200 $\mu$F, 150 V

Answer 1

Answer: (C)

600 $\mu$F, 150 V

Here, $C=4+4=8\mu F$ and $C^{\prime }=\frac{8\times 12}{8+12}=4.8\mu F$
Now capacitors $20\mu F$ and $C^{\prime }$ are in series so potential across $C^{\prime }$ is $V^{\prime }=\frac{20}{20+4.8}\times 310=250V$
As $C$ and $12\mu F$ are in series so potential across $C$ is $V_C=\frac{12}{12+8}\times 250=150V$
As capacitors $4\mu F$ and $4\mu F$ are in parallel so potential across each $4\mu F$ capacitors is equal to $150V$.
Charge on $4\mu F$ is $q=4\times 150=600\mu C$