Two capacitors of capacitances `3 muF and 6 muF`, are charged to potentials 2V and 5V respectively. These two charged capacitors are connected in series. Find the potential across each of the two capacitors now.

Answer

`12 V ; 6 V`

Explanation

Here, `C_(1) = 3 muF, C_(2) = 6 muF`
`V_(1) = 2 V, V_(2) = 5 V`
Before connecting, `Q_(1) = C_(1) V_(1) = 3xx2 = 6 muC`
`Q_(2) = C_(2) V_(2) = 6xx5 = 30 muC`
Total charge, `Q = Q_(1) + Q_(2) = 6 + 30 = 36 muC`
In series combination, charge is conserved,
`:.` Charge on each capacitor, `Q = 36 muC`
Potential of `3 muF` capacitor, `V_(1) = (Q_(1))/(C_(1)) = (36)/(3) = 12 V`
Potential of `6 muF` capacitor, `V_(2) = (Q)/(C_(2)) = (36)/(3) = 6 V`