Question 29: Electrostats & Capacitance

Question

A network of capacitors is as shown below. If the voltage supply is 100 V , find the energy stored in the $6 \mu \mathrm{~F}$ capacitor.

$C_1=3 \mu F, C_2=6 \mu F, C_3=3 \mu F$ and $C_4=4 \mu F$

Accepted Answer

First, conserve charge when the two capacitors are connected in parallel (no external losses).
Initial charge on the 4 ÃÂ¼F capacitor:
$$Q_i = C_1V_1 = (4\;\mu	ext F)(24\;	ext V)=96\;\mu	ext C$$
Total capacitance after connection:
$$C_{m tot}=C_1+C_2=4\;\mu	ext F+6\;\mu	ext F=10\;\mu	ext F$$
Final common voltage:
$$V_f=\frac{Q_i}{C_{m tot}}=\frac{96\;\mu	ext C}{10\;\mu	ext F}=9.6\;	ext V$$
Answer: 9.6 V (Option C).

Answer

1.2 mJ

Answer

12 mJ

Answer

2.2 mJ

Answer

4.2 mJ

Electrostats & Capacitance

A network of capacitors is as shown below. If the voltage supply is 100 V , find the energy stored in the 6 \mu \mathrm{~F} capacitor. C_1=3 \mu F, C_2=6 \mu F, C_3=3 \mu F and C_4=4 \mu F

Choose the correct answer: