Question

Chapter 6: (Total points 20) 5. Two capacitors (25 and 75 uF) are connected to a 100-V source. Find the energy stored in each capacitor if they are connected in: (a) parallel (Points 6) (b) series (Points 6) Soln

Answer 1

If capacitors are connected in parallel Energy stored in capacitor = 1/2 cv^2 Energy stored in 7.5 mu F capacitor = 1/2 times 75 times 10^- 6 times (100)^2 = 375 mJ Energy stored in 25 mu F capacitor = 1/2 times 25 times 10^- 6 times 100^2 = 125 mJ if capacitors are connected in series Energy stored in capacitor = 1/2 Q^2/c = 1/2 cv^2 Q = cv According to voltage to voltage division rule v_1 = 100 times 75/(25 + 75) = 75 v v_2 = 100 times 25/(25 + 75) = 25 v \r\n Energy stored in 25 mu F capacitor = 1/2 times 25 times 10^- 6 times 75^2 = 70.312 mJ Energy stored in 75 mu F capacitor = 1/2 times 75 times 10^- 6 times 25^2 = 23.43 mJ