Question

31. Two capacitors C, 2uF and C, 1uF 100V, but with opposite polarity as shown in the fig. The switches S, and S are closed. The ratio of final energy to the initial energy of the system is charged to same potential V are

Answer 1

Answer:

Explanation:

two capacitors C1 = 2uF and C2 = 4uF are connected in series so, equivalent capacitance is Ceq = C1.C2/(C1 + C2) = 2 × 4/(2 + 4) = 4/3 uF

we know,

Q = CV

where Q is charge , C is the capacitance of capacitor and V is the potential difference.

now, Qnet in circuit = equivalent capacitance of capacitors attached in circuit × potential difference

Qnet = 1200 × 4/3 = 1600uC

both the capacitors are in series so, charge passing through both are same. e.g., Q = 1600uC

hence, Q = CV

here, C = 2uF , Q = 1600 uC

now, V = 1600uC/2uF = 800v

hence, potential difference across 2uF is 800v

Answer 2

Check the attachment :)