Three capacitors of capacitances 25 μF ,30 μF and 45 μF are connected in parallel to a supply of 100 V. Energy stored in the above combination is E. When these capacitors are connected in series to t…

Question

Three capacitors of capacitances 25 μF ,30 μF and 45 μF are connected in parallel to a supply of 100 V. Energy stored in the above combination is E. When these capacitors are connected in series to the same supply, the stored energy is 9xE. The value of x is_____

Accepted Answer

Correct answer: 86. (86) In parallel combination: Potential difference is same across all Energy= 12(C_1+C_2+C_3)V^2 = 12 (25+30+45 ) (100 )^2 10^-6=0.5=E In series combination: Charge is same on all. 1C_ equ= 1C_1+ 1C_2+ 1C_3= 125+ 130+ 145 1C_ equ= (18+15+10 )450= 43450 ⇒C_ equ= 45043 Energy= Q^22C_1+ Q^22C_2+ Q^22C_3 = Q^22( 1C_1+ 1C_2+ 1C_3) (V C_ equ)^22 1C_ equ= V^2C_ equ2 (100 )^22 45043 10^-6 ⇒ 4.586= 9xE= 9x 0.5 ⇒x=86

$Three capacitors of capacitances 25 μF, 30 μF and 45 μF are connected in parallel to a supply of 100 V . Energy stored in the above combination is E . When these capacitors are connected in series to the same supply, the stored energy is \frac{9}{x} E . The value of x is_____$

Solution

More Capacitance PYQs