Three capacitors `C_1,C_2,andC_3` of capacitance `1muF, 2muF, and 3muF`, respectively, are charged separately as shown in the figure. Now these charged capacitors are connected to a battery of `epsilon = 20 V` and an uncharged capacitor of `C = 2muF` as shown in figure.
,
The charge on capacitor marked C is

Options

A. `3.75 muC`
B. `7.5 muC`
C. `15 muC`
D. none of these

Answer

C

Explanation

The circuit can be redrawn as
Conserving charges on lower plates, we get
`-[(x+20)1+(x+2)2+(x+20)3+2x]=-60`
or `x=-(15)/(2)V`
`|Q_(1muF)|=12.5muC`
`|Q_(2muF)|=25muC`
`|Q_(3muF)|=37.5muC`
`|Q_(2muF)|=15muC`