Question

If $-5.4\times {10}^{-x}C$ of charge flows through the switch $S$ when it is closed, find the value of $x$ is.

Answer 1

Initially

$q=C_{net}V=\left(2\mu F\right)\left(18\right)=36\mu C$

Finally

Charge flow from $S=$ (Final charge on plates p and r)-(Initial charges on plates p and r)

$=(-72+18)-(-36+36)$

$=-54\mu C$

so x value is than -5