Engineering Board Exam Reviewer · Time Response of Reactive Circuits · hard
A 10, F capacitor charged to 50 V is connected through a resistor across an identical uncharged 10, F capacitor. How much energy is dissipated in the resistor by the time everything settles?
- 12.5 mJ
- 3.12 mJ
- 6.25 mJ
- 25 mJ
Answer
C. 6.25 mJ
Solution
Charge is conserved, so the final voltage is 25 V on each capacitor. Initial energy = 12(10 )(50)2=12.5 mJ. Final energy =2· 12(10 )(25)2=6.25 mJ. The difference, 6.25 mJ, is dissipated in the resistor (whatever its value).
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