Three capacitors of capacities `8muF,8muFand4muF` are connected in a series and a potential difference of 120 volt is maintained across the combination. Calculate the charge on capacitor of capacity `4muF`.

Explanation

Data: `C_(1) = 8muF, C(2) = 8muF, C_(3) = 4muF, V=120V`
Let `C_(s)`= equivalent capacity of the series combination of the capacitors.
`therefore 1/C_(s) = 1/C_(1) + 1/C_(2) + 1/C_(3)`
`=1/8 + 1/8 + 1/4`
`=(1+1+2)/8`
`=4/8 = 1/2`
`therefore C_(2)=2 muF = 2 xx 10^(-6)` F
In series combination, the charge on each capacitor is the same. It is given by `Q=C_(s)V`
`therefore Q_(s) = Q = 2 xx 10^(-6) xx 120`
`=2.4 xx 10^(-4)` coulomb
The charge on the `4muF` capacitor is `2.4 xx 10^(-4)` C