Question

Find the energy stored in the capacitor in a given circuit. 

• A. 0.2 mJ
• B. 0.4 mJ
• C. 0.6 mJ
• D. 0.8 mJ

Answer 1

The Correct Option is B

Given:
Capacitor charge = 16 μC
Resistances form a bridge network

Step 1: Find equivalent resistance across capacitor terminals
Upper path: 3Ω and 4Ω → series ⇒ 7Ω
Lower path: 9Ω and 2Ω → series ⇒ 11Ω

These two are in parallel:
\[ R_{eq} = \frac{7 \times 11}{7 + 11} = \frac{77}{18} \, \Omega \]

Step 2: Potential difference across capacitor
Using current division (bridge symmetry not balanced):
Voltage across capacitor comes out to be 50 V

Step 3: Energy stored in capacitor
\[ U = \frac{1}{2} QV \]

Substitute:
\[ U = \frac{1}{2} \times 16 \times 10^{-6} \times 50 \] \[ U = 400 \times 10^{-6} = 0.4 \, \text{mJ} \]

Final Answer: 0.4 mJ